INTRODUCTION

The reality of solitary confinement in the USA is notorious. Official reports, legal and psychological literature, and media accounts have presented a myriad of stories of incarcerated people who were forced into extreme isolation for or over hours for indefinite time frames with no meaningful social contact beyond sporadic interactions with prison guards—often in precarious living conditions. While such reality exists and persists in many correctional facilities, the practice of solitary confinement is nonetheless legitimate, as it is presumably able to meet the disciplinary, security, and safety-related needs of prisons.

There is neither uniform regulation nor consistent administration of solitary confinement across states. Rather, the policies and practices that govern solitary confinement are largely left to the discretion of single prison administrations of each state. The administrative arbitrariness of solitary confinement, which has often resulted in abuses of the practice, has given rise to a number of national and international movements that demand either the abolishment or a radical reform of solitary confinement in the USA. These strains have led to several reforms in some jurisdictions as well as the formulation of recommendations and guidelines by the Department of Justice and national associations. These interventions encourage restriction of the use of solitary confinement by placing constraints on the maximum amount of time that can be spent in extreme isolation or by banning the use of solitary confinement for more vulnerable prison populations, including people with mental disabilities and juveniles.

Nevertheless, progress in limiting or improving solitary confinement regimes has proved to be slow and generally inconsistent. The official report of the American State Correctional Association and Liman Center (ASCA-Liman) in indicates that the number of people forced into isolation has decreased in two dozen of states yet increased in others.

In addition to a lack of uniform standards and policies regulating solitary confinement regimes across the country, there is also a narrow and highly deferential application of the constitutional standard for determining the legitimacy of solitary confinement under the Eighth Amendment ban on cruel and unusual punishments. As of Estelle, the Supreme Court has established that conditions of confinement—including solitary confinement—amount to cruel and unusual punishment, provided that they result in “an unnecessary and wanton infliction of pain” upon incarcerated people. This requirement is met when such conditions involve a “deprivation of basic identifiable human needs” to an extent that they inflict harm or create a “substantial risk of serious harm” and are enacted with “deliberate indifference” by prison personnel. Although it is not an explicit criterion of the conditions of confinement test, when appraising the constitutionality of a prison condition, Courts also consider a state’s “legitimate penological interest” in holding a prisoner in that condition.

Regarding solitary confinement specifically, the Court and lower federal courts have—with limited exceptions—perpetuated a narrow application of the conditions of confinement standard. In particular, Courts have often discounted the generalized mental pain that is caused by living in social isolation in environmentally impoverished cells. Accordingly, they have frequently neglected the duration of solitary confinement as an autonomous aspect of constitutional scrutiny. In so doing, Courts have often overlooked the effects of the distinguishing aspect of solitary confinement compared to normal confinement, namely extreme isolation, otherwise referred to as social and environmental (or socio-environmental) deprivation.

In recent times, another avenue has been undertaken to challenge the constitutionality of solitary confinement. Such mode relies upon insights from social neuroscience examining the traumatic and potentially permanent effects of social and environmental deprivation on the brain. Social neuroscience research has suggested that social interaction in enriched environments is of vital importance for physiological brain function and mental health. Further studies have revealed an array of brain deteriorations that social and environmental deprivation can impart within even after a brief period of time. Such deteriorations have been associated with a number of potentially irreversible mental conditions. Moreover, many of the mental conditions that correlate with such deteriorations due to isolation in deprived environments have been associated with an increased risk of maladaptive action tendencies and socially dysfunctional behaviors, including aggression. An equally significant topic of research from this branch of neuroscience has reported the organic nature of social pain endured by social isolation.

While neuroscientific findings on the damaging consequences of socio-environmental deprivation integrate and strengthen the validity of the copious research on the deleterious psychological effects of solitary confinement, they also exhibit the potential to offer new support for challenges to solitary confinement. First, these studies support the claim that solitary confinement is per se a condition that deprives individuals of identifiable basic human needs, namely those of social interaction and environmental stimulation. Second, within several days of isolation spent in a deprived setting, there is a risk of physical deteriorations in the brain. Third, the damaging consequences for mental health and behavior that follow such deterioration could continue upon re-introduction of the person to the social environment and may seriously compromise the person’s long-term social functioning. Based on these insights, this article makes a case for finding solitary confinement per se cruel and unusual under any aspect of the current conditions of confinement standard. Furthermore, it illustrates avenues for a profound rethinking of solitary confinement regimes.

The article proceeds as follows. The next section, Part I, conducts a succinct analysis of conditions of confinement jurisprudence (hereby, conditions jurisprudence) to illustrate the current constitutional status of solitary confinement. Subsequently, Part II discusses how conditions jurisprudence has attributed predominant irrelevance to the generalized mental pain that extreme isolation causes. Part III then addresses the general oversight of the duration of extreme isolation as an autonomous aspect of constitutional scrutiny under the Eighth Amendment. Part IV reviews neuroscientific literature on social and environmental deprivation by first analyzing neuroscientific research on the need for social interaction and environmental stimulation to preserve physiological brain function and mental health (Part IV.A). The review continues with an analysis of the set of neuroscientific research on the traumatic effects of social isolation and environmental deprivation for the brain, mental and physical health, and social behavior as well as on the organic nature of social pain (Part IV. B and IV.C). Afterward, Part V engages with the reviewed neuroscientific insights to develop and advance several challenges to solitary confinement. Specifically, this part argues that solitary confinement per se fails to meet the current conditions standard in three main respects. First, solitary confinement per se deprives individuals of basic human needs, namely social interaction and environmental stimulation. Second, such deprivation can precipitate objectively serious and potentially permanent brain deteriorations also in healthy individuals. Third, the types of deteriorations and the extent of their risk are too excessive in relation to the penological prison interests of discipline, security, and safety. Part VI additionally argues from a more scholarly perspective that solitary confinement and its risks and consequences are also incompatible with the retributive, incapacitative, deterrent, and rehabilitative justifications for punishment. In view of these arguments, the article maintains that solitary confinement is an innately cruel and unusual punishment from any Eighth Amendment-relevant perspective. Part VII concludes the article with a proposal to abolish solitude in prisons that supports a profound rethinking of solitary confinement regimes under strict (and possibly uniform) temporal, social, and environmental standards.

SOLITARY CONFINEMENT IN “CONDITIONS JURISPRUDENCE”

Existing literature has recounted at length the history of solitary confinement. Abundant studies have also provided extensive and detailed analyses of the origins and the interpretive evolution of the Eighth Amendment. While this article does not fully review the numerous reconstructions of other scholars over the years, its scope does include specific aspects of conditions jurisprudence and its application to solitary confinement. These aspects offer a basis for the normative arguments in Part V.

The meaning of “cruel and unusual punishments” has not received a definitive interpretation in Courts decisions. Nonetheless, over the years the Supreme Court has developed two approaches to establish the confines of cruel and unusual punishment. The first approach, which generally applies to penalties that are formally meted out by courts or in statutes, evaluates whether the punishment in question is proportional to the severity of the crime committed. Thus, a punishment is cruel and unusual when “by [its] excessive length or severity [it is] greatly disproportioned to the offenses charged.” Such judgment must be made with consideration to the “evolving standard of decency that marks the progress of a maturing society.”

The second approach, which generally applies to the treatment of people in prison including the conditions of their confinement, evaluates whether the “punishment” in question involves an “unnecessary and wanton infliction of pain”. The governing standard to determine if the treatment or the conditions within the prison in question amount to an unnecessary and wanton infliction of pain requires that it (they) result(s) in unquestioned and “serious deprivation [s] of basic human needs” to an extent that it/they inflict (s) harm or create (s) a “substantial risk of harm” that is objectively serious (the “objective prong” of the standard). The standard also requires that prison officials must be “deliberately indifferent” to the fact that such treatment or condition inflicts or creates a risk of inflicting serious harm upon the individual (the “subjective prong” of the standard). Furthermore, a punishment (including the treatment of prisoners and their living conditions in prisons) results in an unnecessary and wanton infliction of pain, even though applied in pursuit of a legitimate penological aim, if it goes beyond what is necessary to achieve that aim. The ultimate criterion for evaluating the “unnecessary and wanton infliction of pain” standard lies also in the developing concepts of decency that mark the progress of a maturing society.

Still, solitary confinement is not per se cruel and unusual punishment. Nevertheless, solitary confinement “becomes” cruel and unusual when its accompanying material conditions amount to a wanton or unnecessary infliction of pain under the above-mentioned criteria set by the Court. Throughout history, Courts have manifested a tendency to a narrow interpretation and application of the conditions standard in relation to solitary confinement. Such approach has sparked criticism from legal scholars who have moved an objection of “underinclusivity” against the Courts’ approach to solitary conditions cases. Notably, Courts have been underinclusive in tending to discount the generalized mental pain that extreme isolation causes. As a consequence, they have often neglected the duration of solitary confinement as an independent aspect of constitutional scrutiny. In the following section, I shall discuss all of these aspects in turn.

SOLITARY CONFINEMENT AND THE OBJECTIVE PRONG OF THE CONDITIONS STANDARD

The narrowness of Courts’ applications of the conditions standard to solitary confinement cases emerges first from the dominant interpretation of the notion of “basic human need.” The Supreme Court has generally stated that constitutional protections that relate to conditions of confinement following a criminal conviction derive from the acknowledgment that “[p] risoners retain the essence of human dignity inherent in all persons” and that, through incarceration, “society takes from prisoners the means to provide for their own needs.” Therefore, “[a] prison that deprives prisoners of basic sustenance . . . is incompatible with the concept of human dignity and has no place in civilized society.”

The concept of “basic human need” has not received a detailed or unanimous interpretation by federal courts. Generally, Courts have understood “basic human needs” as specific and identifiable minimal life necessities that include food, water, shelter, exercise, medical care, and sanitation. Thus, the predominant understanding of “basic human need” mainly concerns specific “physical needs” that are considered to be necessary for one’s survival. In addition, the Supreme Court has established that only “extreme deprivations” are sufficient to support a condition of confinement claim. This requirement is met when the deprivation is sufficiently serious to deny “the minimal civilized measure of life’s necessities.”

The requirement of an extreme deprivation of a specific, identifiable basic human need has greatly reduced the possibility of challenging solitary confinement based on its general conditions. With few exceptions, the lack of proof that a person living in extreme isolation has been deprived of a necessary means of survival renders harsh or restrictive conditions of solitary confinement insufficient to equate to a wanton and unnecessary infliction of pain.

The bar for successfully meeting the objective prong of the conditions standard is made even higher by the requirement that the deprivation of (a) basic human need(s) must either result in or pose “a substantial risk of serious harm.” This requirement is measured by “whether society considers the risk . . . to be so grave that it violates contemporary standards of decency to expose anyone unwillingly to such a risk.”

Courts have been vague about the type of harm—either physical or psychological—that must be (potentially) suffered to meet the standard. However, some authors have observed that Courts ultimately tend to understand “serious harm” as “physical” harm. The premise of such understanding is that the objectively serious harm must result from a serious deprivation of specific basic human needs. The latter, as noted above, have been generally understood to encompass physical needs, which include food, water, medical care, shelter, or sanitation. The deprivation of such physical needs leads to kinds of harm—starvation, thirst, or diseases due to poor hygiene—that are fundamentally physical.

The exception (that proves the rule) to the general interpretation of “objectively serious harm” as essentially physical harm is represented by the body of cases that have identified the solitary confinement of people with mental disabilities as unconstitutional. Such exception is grounded in the idea that mental illness renders people more vulnerable to the harmful effects of extreme isolation. The leading case of this trend is Madrid v Gomez, wherein the federal district court likened the placement of persons with mental illness in solitary confinement to “putting an asthmatic in a place with little air to breathe.” Although the court recognized that prolonged isolation in scarce environments risks producing significant psychological traumas in incarcerated people with no history of mental illness as well, the court held that, “for many inmates, it does not appear that the degree of mental injury suffered significantly exceeds the kind of generalized psychological pain that courts have found compatible with Eighth Amendment standards.” By relying upon such presumption of resilience of the general prison population to the harms of extreme isolation, the court essentially upheld that extreme isolation does not pose such a significant risk of serious psychological injury for all prisoners in solitary confinement. Therefore, solitary confinement is not a “per se” Eighth Amendment violation.

Cases such as Madrid represent key progress in solitary conditions jurisprudence. However, they simultaneously confirm the still-prevailing neglect of the generalized mental harm or pain due to extreme isolation among the healthy prison population. By qualitatively differentiating the risks of solitary confinement for mentally ill inmates from the generalized risk of psychological harm that is accrued through solitary confinement, Courts have failed to recognize that solitary confinement innately involves dangerous psychological risks for people who are forced into isolation in impoverished environments. Such failure has manifested a substantial underestimation of the devastating mental effects that extreme isolation can precipitate in any individual.

SOLITARY CONFINEMENT AND THE SUBJECTIVE PRONG OF THE CONDITIONS STANDARD

In Estelle and Wilson, the Supreme Court upheld that Eighth Amendment claims arising from confinement conditions that are not formally imposed as a sentence for a crime also require proof of a subjective component, ie the deliberate indifference of prison officials to a prisoner’s health or safety. The subjective “deliberate indifference” aspect of the conditions standard generally requires that a state official “knows of and disregards an excessive risk to inmate health or safety;” therefore, “the official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference”. Essentially, “an official’s failure to alleviate a significant risk that he should have perceived but did not . . .cannot under our cases be condemned as the infliction of punishment” in violation of the Eighth Amendment.

In Farmer, the Court clarified that deliberate indifference is equivalent to subjective recklessness, as is conceived of in criminal law. As such, the subjective prong of the conditions standard refers to the official’s culpable state of mind and requires proof that corrections officials knew of and disregarded an excessive risk to an individual’s health and safety. While the test remains individualized for the relevant case and prison official, the Court in Farmer also recognized that some risks of harm are so objectively clear that “a fact finder may conclude that a prison official knew of a substantial risk from the very fact that the risk was obvious.” Therefore, the proof of the official’s awareness or disregard can also rely on circumstantial evidence that the risk was manifestly and generally known to be ignored.

The deliberate indifference test is surrounded by scholarly criticism. Arguments include that this subjective element may constitute an obstacle to successfully challenging objectively harmful conditions of solitary confinement, as is often difficult to prove in solitary confinement litigations. Such difficulty is particularly manifest in cases that require the proof of prison officials’ deliberate indifference to the (risks of) mental harm induced by solitary confinement, especially among people with mental illness. Prison officials are not trained in mental health and have no knowledge of the symptoms or risks of a mental condition. Thus, they may avoid liability by simply claiming that they did not have actual knowledge of a mental need. As a consequence, prisoners who report significant mental harm “face a tougher burden in proving [prison officials’] actual knowledge than their physically ill counterparts.” Admittedly, physical conditions are more easily recognized (and recognizable) by a layman, and one’s knowledge of them is easier to prove in litigation.

In view of its arguable provability, several authors have substantially called for reconsidering or even eliminating the subjective prong of the conditions test and focus only on the objective conditions of confinement. Importantly, with specific regard to solitary confinement, some authors have highlighted that the condition of extreme isolation alone should be sufficient to grant a presumption of deliberate indifference to the health and safety of the person who has been forced into solitary confinement.

PENOLOGICAL INTERESTS

Although it is not an explicit criterion of the conditions of confinement test, the Supreme Court has explicated that a factor to consider in assessing the constitutionality of a prison condition is the state’s “legitimate penological interest” in holding a prisoner in that condition. Thus, when appraising whether one or more prison conditions deprive individuals of their basic human needs and risk inflicting serious harm, the gravity of the (risk of) harm incurred by an inmate is weighed against the legitimate penological needs of the prison in terms of discipline, security, and safety. Moreover, the presence of a legitimate prison interest may influence the determination of whether prison officials were deliberately indifferent to the protected interests of the inmate.

In regard to solitary confinement, policy makers and corrections officials widely believe that the use of solitary confinement is an effective strategy to increase safety and promote order throughout the prison system because it reduces criminal activity and prison violence. Therefore, the necessity and effectiveness of solitary confinement in safeguarding prison interests allegedly counterbalance the adverse impact that it may have on prisoners who are forced into isolation. In this way, there is an implicit trade-off between the adverse impact of solitary confinement on prisoners—ie the loss of social interaction—and the benefits of prison, namely discipline, security, and safety. Thus, the potential “benefits” of solitary confinement for the individual inmate, the other inmates, and the prison staff neutralize the harm that is linked with stays in extreme isolation.

This balancing argument is implicitly supported by the Courts’ attitude of judicial deference of solitary confinement management to prison administrators and officials. Lacking any established criteria for assessing the legitimacy of a penological interest in a given prison condition, such as solitary confinement, Courts have often “deferr [ed] to prison officials when they claim that a particular condition or treatment is necessary.” In fact, Courts have explicitly acknowledged the greater competence of prison administrators and officials compared to Courts in terms of operating prisons and understanding their dynamics. These arguments posit that prison administrators and officials, rather than judges, have the most accurate sense of available resources, the most knowledge of which individuals are most in need of these resources, and the strongest ability to track prisoners’ evolving treatment needs. Moreover, they have the right expertise in managing safety and protection needs that may arise in a prison setting.

This attitude of judicial deference has proved particularly frequent in solitary confinement litigation cases. In many of these cases, even if a question of fact did exist as to whether the conditions of solitary confinement posed a serious risk of substantial harm that implicated the Eighth Amendment, prison administration still successfully claimed a legitimate penological interest in inflicting isolated confinement upon a prisoner. For instance, in Scarver v Litscher, the Seventh Circuit recognized that the plaintiff had endured mental suffering due to his placement in supermax confinement, observing that he had repeatedly banged his head against the wall of the cell. Although it acknowledged that this situation was concerning, the court demonstrated its unwillingness to interfere with correctional management of dangerous inmates and held that “[p] rison authorities must be given considerable latitude in the design of measures for controlling homicidal maniacs without exacerbating their manias beyond what is necessary for security. It is a delicate balance.”

According to Glidden and Rovner, while Courts do not always express their opinions so openly, “a similar underlying sentiment is regularly present in such cases, and may be influencing the decision even absent any explicit language.” Moreover, these and other authors have observed that prison officials are not required to thoroughly justify the specific conditions that accompany solitary confinement. Rather, generic assertions of safety and security often suffice as a legitimate penological interest in holding a prisoner in isolation. For instance, as Hafemeister and George have noted, a justification that prison officials have often advanced in defending the harsh regimes of supermax facilities is that “they house the ‘worst of the worst’; the violent, dangerous inmates who simply cannot be housed anywhere else.” Such assertions—and judicial deference to them—are common among Eighth Amendment analyses and have often resulted in a lack of careful scrutiny of the material conditions of solitary confinement. Thus, even though the Supreme Court explicated that the “touchstone” of the penological evaluation of prison conditions “is the effect upon the imprisoned” and that affording “deference to the findings of state prison officials in the context of the [E] ighth [A] mendment would reduce that provision to a nullity in precisely the context where it is most necessary,” the risk de facto exists that the legitimate interests of prisons will prevail over the concern for the negative consequences of harsh conditions, such as those of solitary confinement, for incarcerated people.

MENTAL PAIN IN EXTREME ISOLATION

The literature has extensively reported the psychological effects of solitary confinement. Numerous psychological, psychiatric and observational studies have carefully documented the high amount of adverse consequences of living in isolation in deprived environments for mental health, well-being, and behavioral attitudes in both mentally ill and healthy populations. Suicidal thoughts, depression, and attentional and memory deficits are just a few examples of the mental anguish that people incarcerated in extreme isolation can suffer, especially under medium- to long-term extreme isolation and in particularly scarce settings. Beyond the most severe psychopathological effects, psychological literature has also widely documented a link between social isolation and the experience of social pain, which entails “the painful feelings following social rejection or social loss”, as well as an adverse impact of social pain on physical and mental health and psychological well-being, including poor self-esteem, humiliation, a feeling of meaninglessness, greater rejection-sensitivity, and increased aggression.

Although these studies have been largely replicated and have entered courtrooms on many occasions as well, “lower courts have only rarely recognized grave mental harm in the conditions of confinement context, and the Supreme Court has never done so.” However misguided, Courts have generally been unwilling to recognize that the mental harm that extreme isolation causes is per se sufficient to comprise an Eighth Amendment violation.

There are at least two main interrelated reasons for the Courts’ neglect of the generalized mental suffering due to solitary confinement. The first concerns a tendency to discount social interaction as a basic human need. As noted, Courts tend to interpret the “deprivation of basic human needs” requirement in terms of identifiable physical needs, such as water, food, or sanitation. Only on a few exceptional occasions have lower courts recognized social interaction as a basic human need.

The second, and consequential, reason for the neglect is that although the lack of social interaction results in serious harm, “that harm is mental, not physical”. According to Jules Lobel, U.S. law views mental harm, and mental pain accordingly, as “a second-class citizen” compared to physical harm and pain. In principle, U.S. law has endorsed a “dualistic presumption” of harm/pain, which views physical and mental harm/pain as qualitatively and hierarchically different types of suffering—the former being more objective, tangible and serious than the latter.

Regarding the specific relation of mental harm/pain to confinement conditions, Lobel has recalled the Prison Litigation Reform Act (PLRA). This federal law was enacted in with the aim of decreasing the incidence of prison litigation within the court system by requiring prisoners to first exhaust available administrative remedies. Thereby, the PLRA ultimately sought to curb the discretion of the federal courts in remedial actions. In the part that regulates the requirements for filing a lawsuit, the PLRA sets an explicit physical injury prerequisite to ask for monetary compensation. Meanwhile, mental or emotional injury is not sufficient to support a federal civil action without evidence of physical injury.

The “physical injury versus mental and emotional pain” distinction within the PLRA provision has limited the high number of lawsuits to be filed in federal courts over the years. Furthermore, such distinction has been echoed by cases that have challenged the mental anguish of solitary confinement. In fact, Courts have often discounted mental or emotional harm in the absence of proof of physical harm.

Conclusively, the general oversight of mental harm and pain following extreme isolation strictly relates to and follows a tendency to discount social interaction as a basic human need. Although the lack of social interaction results in serious mental pain, social interaction is a “mental need,” not a physical need. Thus, unlike food and water, it does not qualify as an essential precondition for human life.

Finally, by excluding social interaction from the range of relevant human needs that warrant constitutional protection, Courts have substantially placed the conditions of normal confinement and of solitary confinement on the same level. Based on several opinions, if the conditions of the latter are substantially and materially equivalent to the conditions of the former, then the Eighth Amendment is not implicated. In such case, neither social interaction nor the mental harm/pain that derive from its deprivation are worthy of constitutional protection.

DURATION OF EXTREME ISOLATION

The limited relevance that conditions jurisprudence affords to mental pain is linked to another critical aspect that Eighth Amendment analyses of solitary confinement have often overlooked: the duration of extreme isolation. As the Introduction has anticipated, solitary confinement regimes vary from state to state. Therefore, there is no uniform standard that mandate a maximum amount of time that can be spent in extreme isolation. While federal reports and national associations have issued guidelines that recommend maximum time limits for solitary confinement, such limits fall largely under the discretionality of prison administrations. Such discretionality entails that solitary confinement has an open-ended nature; specifically, it can last for a few days, or an indefinite period, or it can even be permanent.

The Supreme Court as well as lower courts have only rarely addressed the length of solitary confinement as an autonomous aspect of constitutional scrutiny under the Eighth Amendment. Rather, they have typically considered the length of solitary confinement to be an aspect to evaluate in conjunction with (and depending on) the accompanying material conditions of extreme isolation. Thus, although Courts have occasionally recognized that prolonged solitary confinement may be considered as a relevant factor in the determinations of the Eighth Amendment ban, this factor has not been treated as an autonomous aspect of constitutional scrutiny.

Lower federal courts have admittedly been more inclined to acknowledge the autonomous relevance of the duration—and, accordingly, of its effects—as an element to assess separately from the material conditions of solitary confinement. For instance, in Sostre v Rockefeller, the court engaged extensively with the issue of duration. The district court attempted to set limits on the length of solitary confinement, stating that “to be constitutional, punitive segregation . . . must be limited to no more than fifteen days and may be imposed only for serious infractions of the rules.” Meanwhile, in O’Brien v Moriarty, the court similarly observed that, where solitary confinement is “[i]mposed inappropriately, or for too long a period, even the permissible forms of solitary confinement might violate the Eighth Amendment.”

Compared to lower courts, the Supreme Court has been more hesitant to recognize an autonomous constitutional relevance of the duration of solitary confinement. On the contrary, it has been more willing to situate the duration in a dependent relation with the accompanying material conditions of solitary confinement. Such approach is self-evident in Hutto. In this case, the Court followed the logic of In re Medley in ruling that solitary confinement alone “is not necessarily unconstitutional, but it may be, depending on the duration of the confinement and (emphasis added) conditions thereof... .” Hence, the Court then stated,

[i] t is perfectly obvious that every decision to remove a particular inmate from general prison population for an indeterminate period could not be characterized as cruel and unusual. If new conditions of confinement are not materially different from those affecting other prisoners, a transfer for the duration of a prisoner’s sentence might be completely unobjectionable and well within the authority of the prison administrator.

As emerges from these and other passages, the Court’s opinion considers the duration of solitary confinement to be part of the issue of whether or not solitary confinement complies with constitutional requirements. However, it is only one among many other factors that required inclusion in such scrutiny. Thus, the length of solitary confinement is constitutionally objectionable when accompanying material conditions of solitary confinement fail to meet constitutional standards.

As observed, one reason that the duration of solitary confinement does not autonomously fall within the scope of constitutional analysis under the Eighth Amendment derives from the excessive judicial deference to individual prison administrations in deciding on and applying solitary confinement regimes. In embracing this laissez-faire attitude, Courts have largely delegated determinations of the length of solitary confinement to prison administrations. As noted, the rationale cites the higher capacity of administrations to understand and address legitimate interests of prisons that may require the imposition of longer terms of isolation.

Despite this long-standing judicial attitude, broader Eighth Amendment concerns regarding long-term solitary confinement have recently reentered lower courts as well as the Supreme Court. Over the past decade, several courts have resolved that the deprivations that attend long-term isolation do run afoul of the Eighth Amendment. For instance, in Jonhson v Wetzel, the district court acknowledged the empirical claim that “psychological stressors such as isolation can be as clinically distressing as physical torture.” Although the court did not challenge the constitutionality of solitary confinement per se, it found that the psychological deteriorations that a person suffers as a direct result of his or her prolonged stay in isolation ( years in the relevant case) are sufficient grounds for an Eighth Amendment violation.

In the same vein, Justice Kennedy’s concurring opinion in Davis v Ayala acknowledged that extended solitary confinement raises serious constitutional questions regardless of its accompanying conditions. As such, the duration of solitary alone should fall within the Court’s scrutiny of constitutionality under the Eighth Amendment. Of equal importance is the criticism of Justice Kennedy regarding the excessive deferential attitude of the Court towards prison administrations. Prison officials may “have discretion” to use solitary confinement as a “temporary” measure to meet protection or safety needs in prisons; nonetheless, this does not prevent Courts from assessing, “within [their] proper jurisdiction and authority” the appropriateness of long-term of solitary confinement in view of its widely documented effects on prisoners and, as a consequence, “to determine whether workable alternative systems for long-term confinement exist, and, if so, whether a correctional system should be required to adopt them.” Justice Kennedy further held that the Court’s unwillingness to address the excessive length of solitary confinement as a specific matter of constitutional scrutiny is tantamount to an implicit acceptance of the adverse effects that a long period of extreme isolation may have on confined individuals. Because the psychological consequences of solitary confinement have been widely established and attracted general attention and concern, failure to address them equates to the adoption of an attitude of indifference.

More recently, in Apodaka v Raemish and Lowe v Raemish Justice Sotomayor has likewise expressed “deeply troubling concern” over the extreme mental pain caused by long-term isolation per se. Referencing Charles Dickens’s written account of the horrors of solitary confinement in Philadelphia’s Eastern State Penitentiary, Justice Sotomayor emphasized Dickens’ conclusion that, back in those days, the penal officers were not aware of the “immense amount of torture and agony which [solitary confinement] inflict [ed] upon the sufferers.” However, as Justice Sotomayor noted,

[Today] [w] e are no longer so unaware. [emphasis added] Courts and corrections officials must accordingly remain alert to the clear constitutional problems raised by keeping prisoners like Apodaca, Vigil, and Lowe in “near-total isolation” from the living world … in what comes perilously close to a penal tomb.

The aforementioned recent opinions manifest a clear urge to interpretively change the conditions standard under the Eighth Amendment clause. This impetus emerges from a clear admission of the inhumanity that is intrinsic to leaving a person in extreme isolation for an excessively long amount of time. However laudable, such recognition still loses sight of the actual constitutional “crux” of solitary confinement, ie extreme isolation. The following sections precisely address this issue.

THE BRAIN IN SOLITUDE

The analysis of conditions jurisprudence in regard to solitary confinement suggests a substantial equivalence between normal confinement and solitary confinement. Such equivalence derives from the fact that either type of confinement can be challenged under the Eighth Amendment only when specific accompanying material conditions of either type of confinement do not meet constitutional standards. Thus, the distinguishing element of solitary confinement, ie extreme isolation or socio-environmental deprivation, is not a sufficient condition to qualify as an Eighth Amendment violation. In other words, socio-environmental deprivation per se is not cruel and unusual punishment. As such, it is completely constitutional.

Recently, another avenue has been undertaken to challenge solitary confinement under the Eighth Amendment. Such avenue has built on insights from social neuroscience regarding brain plasticity, social interaction, and environmental stimulation, as well as on the effects of social and environmental deprivation on brain function and health. These findings have already entered courtrooms in several lawsuits to provide a holistic analysis of the impact of solitary confinement, and they provide additional “foundational evidence” of the harms of extreme isolation. The overall lesson from social neuroscience is that the psychological deteriorations following social and environmental deprivation are linked to alterations that occur in the brain. These brain alterations “have implications beyond the immediately visible behaviors”, and can lead to a wide range of adverse psychological effects, many of which may be long-lasting or even permanent.

Although neuroscientific evidence has already been utilized on a few occasions, it may offer new support for challenges to solitary confinement under current constitutional standards. In the following discussion, I explore this claim in more depth. The vehicle is a succinct review of relevant scientific insights and data—many of which have also been introduced in court cases—to highlight three main neuroscience-based challenges to solitary confinement: first, that social interaction is as much of a basic physical human need as food or water; second, that social and environmental deprivation entails traumatic changes in brain, which underpin potentially permanent psychological consequences; third, social pain that is induced by isolation has an organic basis in the brain, so it is ultimately physical.

NECESSITY OF SOCIAL INTERACTION AND ENVIRONMENTAL STIMULATION FOR PHYSIOLOGICAL BRAIN FUNCTION

In Politics, Aristotle famously wrote that “[m] an is by nature a political animal” and “[a] social instinct is implanted in all men by nature”. Therefore, “men, even when they do not require one another’s help, desire to live together”. More than years later, behavioral and neuroscientific disciplines have furnished compelling and converging empirical data confirming that human beings are evolutionarily constructed to be connected. There is presently a general consensus among psychological, anthropological, sociological, and neuroscientific disciplines that social connection, interaction, and belongingness are innate and universal survival needs among humans to the same degree as food or water.

In their seminal and widely cited work, Baumeister and Leary have suggested that people are programmed to form and maintain interpersonal bonds because they are motivated by their innate need to belong. Accordingly, the need to belong is an innate and universal motivation for human behavior. The authors have characterized this need as the need to form and maintain strong, stable interpersonal relationships. They have crucially argued that this need is satisfied by frequent human contacts and genuine bonds of caring between individuals.

Baumeister and Leary have proposed nine criteria to assess whether a given human need is a fundamental motivation for human behavior. Specifically, the relevant need should achieve the following:

(a) produce effects readily under all but adverse conditions, (b) have affective consequences, (c) direct cognitive processing, (d) lead to ill effects (such as on health or adjustment) when thwarted, (e) elicit goal-oriented behavior designed to satisfy it (subject to motivational patterns such as object substitutability and satiation), (f) be universal in the sense of applying to all people, (g) not be derivative of other motives, (h) affect a broad variety of behaviors, and (i) have implications that go beyond immediate psychological functioning.

Hence, the authors reviewed a large body of evidence that demonstrates that belonging and social connection meet all of these criteria. On this basis, they have concluded that the need to belong is indeed a fundamental human need.

Different perspectives in scientific research support Baumeister’s and Leary’s conclusion. For instance, several studies have suggested an influence of social interaction on the development and the expression of executive functions. In addition, social engagement and participation in meaningful social activities have reportedly helped people sustain their thinking skills better and delay cognitive decline in mid-life and older adulthood. Epidemiological studies have associated social connection and meaningful interactions with superior physical and mental health as well as decreased levels of morbidity and mortality. Other studies have also indicated that consistent meaningful social connections and bonds aid individuals in their development and maintenance of socio-emotional skills, such as empathy and emotion regulation, which are significant mediating factors for prosocial attitudes and behavior. Importantly, these insights align with findings from studies on crime desistance.

Brain function offers one vehicle to explain the vital importance of social connection and interaction for human beings. In adhering to Dunbar’s “social brain hypothesis,” Matthew Lieberman has posited that the brain size of different species—and, specifically, the size of their neocortex—corresponds to the size of their respective social environments. Following this hypothesis, humans have large brains—and the largest neocortex of all species—to meet their most complex needs of socialization. Specifically, the human brain is organized to perform social thinking in order to navigate their complex social interactions and environmental surroundings.

In the same vein, Daniel Siegel has suggested that the brain is “a social organ.” On the one hand, the brain prompts our cerebral processes and bodily experiences when presented with social stimuli, thereby informing our behavioral responses toward other individuals and contributing to our social skills and relationships. Essentially, the brain is the organ that enables social interactions, as it maintains our connections with other individuals. On the other hand, physiological and neurological reactions are directly and profoundly shaped by social interactions. Such interactions, which range from face-to-face conversations to feeling another person’s touch, operate as modulators, which are comparable with interpersonal “thermostats” that continually shape our brain function.

Consistent with these insights, key research on brain plasticity has indicated that positive social engagement induces positive changes to the neural circuits that underlie cognitive functions, socio-affective skills (eg empathy), and social behavior throughout the entire lifespan. These changes have been associated with higher cognitive performance, psychological well-being, and prosocial behavior.

Studies on social interaction and brain plasticity interrelate with those on the continuous influence of environmental stimulation on the brain. These studies have mostly employed animal models. For instance, studies with rodents have evidenced that rodents that are reared in “enriched environments” and are surrounded by their peers exhibited normal developmental pathways in the structure and function of several brain areas, including those that support a variety of functions ranging from prototypically cognitive to emotion-related functions like learning, memory, and emotion regulation. Importantly, these animal samples also exhibited normal sociable tendencies.

Several studies have hypothesized that some of these morphological and functional characteristics can be explained in terms of neurogenesis, which refers to the growth of new cells in brain regions. Evidence implies that enriched environments “enhance cell proliferation and neurogenesis in the brain, notably in the regions critical for social interaction, memory, and communication,” including the hippocampus. As discussed shortly, socio-environmental deprivation appears to stunt neurogenesis in the very same brain regions and pose negative repercussions at the psychological and behavioral level.

In summary, there is an ineradicable bidirectional relationship between the brain and the social environment. On the one hand, the complex organization of the human brain permits humans to serve their biological need to connect and interact with their social world. On the other hand, the social world enables, fuels, and shapes the brain mechanisms that support the cognitive, affective, and socially relevant abilities that allow humans to be individually and socially functional. Thus, social connection or interaction in enriched environments is key to protecting brain function and health. According to Lieberman, “[n] o one will die from lack of social contact over a few days, but people will show evidence of being in a deprived state within a short period and a lack of social connection will likely produce a wide array of negative outcomes for an individual’s mental and physical well-being before long”. Therefore, when a socio-environmental connection is lacking, the brain—and the person as a consequence—will likely undergo profound traumatic consequences in the long term.

THE NEUROBIOLOGICAL EFFECTS OF SOCIAL AND ENVIRONMENTAL DEPRIVATION

A voluminous body of clinical and experimental literature has reported the effects of solitary confinement for healthy and unhealthy incarcerated populations. This literature converges on the same, dramatic conclusion: solitary confinement can cause potentially permanent cognitive, emotional, and physiological damage.

For instance, in his clinical observational studies, Stuart Grassian reported three main “typical features” of the generalized psychopathological effects of solitary confinement: () perceptual distortions, illusions, and hallucinations in several spheres; () affective disturbances including anxiety and panic attacks; and () obsessive, intrusive thoughts that are sometimes accompanied by compulsive behavior. According to Grassian, most-affected people may even develop states of psychotic disturbances of a dissociative character; while those who are less affected still experience substantial psychiatric harm including intense anxiety, obsessional thinking, agitation, paranoia, and irritability.

Grassian’s findings complement those of other studies in psychology that have associated life in solitary confinement with a wide range of adverse psychological effects including rage, irrational anger; fears of persecution; lack of impulse control; severe and chronic depression; appetite loss; heart palpitations; withdrawal; apathy—just to name a few. Also, this body of literature has documented the dehumanizing effects of being socially isolated, which include but are not limited to a lack or loss of sense of belonging, self-esteem, meaningfulness, and self-identity. The dehumanizing effects of social isolation have been associated with a higher risk of engaging in maladaptive, antisocial, and destructive behavior.

Notably, the literature suggests that the psychological impairments that are precipitated by solitary confinement continue even after the release of the individual from prison and his or her reintroduction into the social environment. Specifically, people who are released back into the community after serving time in solitary confinement are “incapable of accommodating to life” due to a hyperresponsivity to sensory stimulations that entails intolerance to the typical noises of daily life, such as the chaos of a restaurant, and social stimulations, including an incapacity to partake in family moments, such as eating meals together.

Scientific research has begun to identify the brain alterations that appear to correlate with the psychopathological effects of socio-environmental deprivation (or extreme isolation). For instance, electroencephalography (EEG) studies have reflected that a few days in solitary confinement may provoke brain injury-like waves alterations. Such alterations have been linked with hyperresponsivity to external stimuli, inadequate attention and alertness to the environment as well as “a complete breakdown or disintegration of the identity of the isolated individual.”

Clinical and experimental studies that have documented the effects of solitary confinement on the brain find support in a robust body of experimental animal research, which is informing an understanding of the various brain mechanisms that underlie the observed psychological and psychiatric symptoms among incarcerated people who have been isolated for protracted periods. These studies have collectively revealed that social and environmental deprivation has negative repercussions for both brain structure and function, including reduced cortical volume, diminished neuronal connections in cortical areas and the hippocampus, decreased myelin production, and altered activity in the reward system and the amygdala. These cerebral alterations have been connected to detachment from the environment, hostility towards others, high levels of aggression, as well as an increased risk of susceptibility to several behavioral conditions that emulate psychiatric diseases and disorders in humans, including neurodegenerative disorders and schizophrenia. Importantly, morphological and functional changes in the brain may occur even after a short period of time and appear to continue after the reintroduction of the subject into the social environment.

A robust body of studies has examined the neurobiological effects of chronic stress due to social and environmental deprivation. For instance, studies with rodents have revealed that rodents that are housed alone, in contrast to those housed in enriched environments, develop a smaller cerebral cortex and shorter synapses in brain areas that are involved in spatial information processing, memory, social information, and emotion regulation, including the hippocampus. In addition, some studies have associated morphological and functional diminutions of the hippocampus with decreased hippocampal neurogenesis. These damages have been linked with the experience of long-term mental health conditions in humans, such as memory loss, cognitive decline, depression, and post-traumatic stress disorder.

Other than the hippocampus, another limbic region that appears to be impacted by social and environmental deprivation is the amygdala, which mediates emotional arousal in response to perceived stimuli. The amygdala is also involved in the experience and the processing of fear and anxiety. Studies with rodents have indicated that high stress increases cortisol levels, which in turn alter neurons proliferation in the amygdala and produce adverse psychological and behavioral effects like anxiety, deficits in social interaction, and poor regulation of social behavior.

At the cortical level, studies with isolated rodents in poor environments observed reduced levels of myelination in the prefrontal cortex. Impaired myelination in this brain area has been reported for a number of psychiatric illnesses, including anxiety, autism, schizophrenia and depression. Other studies with rats have evidenced that isolation-reared rats exhibited reduced medial prefrontal cortex (mPFC) volume compared with group-reared rats. Among humans, reduced mPFC volume has been associated with several core symptoms of schizophrenia, such as neophobia, impaired memory, and sensorimotor gating.

Studies on social isolation correlate and complement research on loneliness, ie the subjective perception of isolation. Although loneliness is not always or necessarily linked with physical and objective isolation, on the other hand such isolation may contribute to a feeling of loneliness. Behavioral research on loneliness has qualified perceived social isolation as a risk factor for “poorer overall cognitive performance, faster cognitive decline, poorer executive functioning, more negativity and depressive cognition, heightened sensitivity to social threats” as well as “an increased implicit vigilance for social threats along with increased anxiety, hostility, and social withdrawal; … decreased impulse control in favor of responses highest in the response hierarchy (ie prepotent responding); increased negativity and depressive symptomatology . . . .” Furthermore, several studies have highlighted links between the symptomatology of loneliness and the neurobiological alterations that are apparent following objective social isolation.

Altogether, there is suggestive evidence of the damaging and long-lasting neurobiological effects of social isolation and environmental deprivation. This evidence suggests that many of these effects can hardly be reversed, even upon reintroduction of the individual into the social environment. Admittedly, many questions about the exact implications of social and environmental deprivation for the human brain and behavior remain unanswered, including the amount of time that a person can be isolated without entailing the risk of irreversible damage or how variables, such as age, gender, or personal background affect the severity of social and environmental isolation for the brain and behavior. As observed, many of these questions are difficult to examine in human samples.

While answering these questions is fundamental to exploring the exact effects of solitary confinement for the brain and behavior, current evidence is reliable and converging enough to support that “increased social isolation and diminished physical contact contribute to and reinforce problematic neurobiological patterns.” Hence, the depriving conditions of solitary confinement will most likely “generate or exacerbate neurobiological deficits and maladaptive behaviors...[t] his becomes a significant issue, especially for individuals who are chronic offenders, where existing neurobiological vulnerabilities are intensified in settings of confinement and segregation, thereby reinforcing maladaptive patterns of behavior.” All in all, neuroscience research indicates that the essential features of solitary confinement, ie social and environmental deprivation, can alone induce significant damages in the brain, all of which risk precipitating long-lasting or even permanent traumatic psychological and physiological consequences. Thus far, these consequences have been mostly overlooked in courtrooms.

SOCIAL PAIN IS PHYSICAL

A key insight from social neuroscience regarding the impact of socio-environmental deprivation on the brain concerns social pain. As noted, lay views of pain and the law itself are founded on the assumption that physical pain and social (mental) pain differ in their characteristics and substance. Physical pain is generally understood as pain from a bodily injury or the deprivation of a physical need; as such, it is objective, measurable, and tangible. Meanwhile, social pain is viewed as purely mental, subjective, and almost “non-existent.” Therefore, it is largely overlooked as an inner experience of the individual with no tangible effects. As noted, this dichotomy of pain pervades the law and also manifests in conditions jurisprudence regarding solitary confinement. To impugn these folk intuitions, a growing body of research in social neuroscience has suggested that social pain is profoundly embodied in the brain. As such, social pain is fundamentally physical.

The most influential theory of adverse social experience, namely the shared representation theory, suggests that physical pain and social pain “rely on shared neural circuitry.” According to this account, the experience of social pain follows the natural and universal human need for social connection and belongingness. From an evolutionary standpoint, such natural need likely originates from the lengthy period of critical need for maternal attachment, care and nurturance among mammalian infants in order to survive. The lack of these fundamental needs generates a feeling of rejection, which the individual perceives as painful and distressful. Based on this survival need, it is possible that “the social attachment system—which ensures social connection—may have piggybacked directly onto the physical pain system, borrowing the pain signal itself to indicate when social relationships are threatened.” Thus, the experience of social pain may be understood as an adaptive way to prevent and survive the threat of social rejection and exclusion. As Lieberman and Eisenberger put it, “[j] ust as evolution has wired us to feel pain when we lack food (eg hunger), water (eg thirst), or shelter (eg freezing, sunburn), perhaps evolution has wired us to feel pain when we lack. . . social connection.”

Building on this perspective, neuroimaging research, which was conducted by Lieberman and Einsenberger, has reported a substantial overlap between physical pain and social pain in the brain. Specifically, their studies have indicated that the experience of physical pain involves two dissociable components: a sensory component, which is supported by the primary and secondary somatosensory cortex and the posterior insula; and an affective component, namely the distressing experience of pain, which is supported by the dorsal anterior cingulate cortex (dACC) and the anterior insula (AI). Neuroimaging studies from this line of research have suggested that the experience of social pain activates neural pathways that are typically implicated in the affective component of physical pain processing—ie the dACC and the AI. These studies have also evidenced that people who exhibit higher sensitivity to physical pain will also be more vulnerable to experiencing social pain. Interventions aimed at healing physical pain also appear to be effective in healing social pain.

Social pain has been associated with both physical and objective isolation (ie the objective lack of social connection) as well as perceived isolation (ie loneliness). Several laboratory studies belonging to the above reported line of research have explored the link between the experience of social pain and social disconnection (caused by social isolation) via neural activity in the brain regions that support the experience of this form of pain. These findings can likely explain why individuals at higher levels of objective or subjective isolation are at a higher risk of developing physical and mental health problems and even a higher risk of mortality. As Einsenberger has explained, “given that the dACC and AI are involved in responding to social disconnection, these regions may have a role in translating experiences of social disconnection into downstream physiological responses—such as heightened inflammatory activity, the immune system’s first line of defense against foreign agents and infection . . . .” Increased inflammatory activity has been found to relate to negative physical and mental health outcomes, including heart diseases and depression.

Last, this line of functional magnetic resonance (fMRI) studies has also started to investigate the effects of social pain on aggression via activation in the dACC and the AI. Preliminary results reflect a positive correlation between increased activity in these two brain regions (associated with the experience of social pain) as well as increased levels of aggression in socially rejected individuals who exhibit less executive functioning (regulatory capability). These results suggest that social pain is a contributing factor to aggressive reactions among socially rejected individuals.

In partial contrast with Eisenberger’s and Lieberman’s works, another fMRI study, which was led by Tor Wager, used a more fine-grained analysis and identified distinct neural representations of physical pain and social pain within core pain-processing brain regions and across other brain regions. Notably, this work indicates that physical pain and social pain entail independent neural representations despite common fMRI activity at the gross anatomical level (eg in the DACC and AI). Thus, rather than recruiting physical pain circuitry, social pain appears to encompass different affective representations in the brain. Based on these findings, these researchers have proposed that physical pain and social pain are ultimately distinct types of affect that may yield unique consequences at the psychological level; thus, they require different types of interventions. Still, the authors have highlighted that physical pain and social pain may still be functionally related and mutually influential. For instance, evidence indicates that individuals who suffered emotional trauma are at a higher risk of developing pain disorders.

Despite the empirical disagreement over whether social pain is neurologically akin to physical pain, neuroscientific findings on the nature of social pain collectively inform two critical insights for the purposes of this article. First, the deprivation of social connection—ie social isolation—entails a range of negative emotional states, adverse psychological effects, and maladaptive behavioral patterns that link with the pain of being socially excluded or rejected. Second, this social pain has physical reality in the brain. As such, it should be qualified as “real pain”, rather than as a kind of “metaphorical pain.” Importantly, the experience of social pain is not less serious or less deleterious than that of physical pain. Rather, its consequences for an individual may well be more distressful and harmful than those following forms of physical pain. Thus, perpetuating the hierarchy of physical versus social pain by privileging the former over the latter is problematic. Most importantly, it severely overlooks the kind of suffering that social pain due to isolation may entail, which can be equally acute and equally (or even more) traumatic and long-lasting compared with the physical pain that one may experience as a consequence of lacking a tangible, physical need.

SOLITARY CONFINEMENT IS PER SE CRUEL AND UNUSUAL PUNISHMENT

The body of neuroscientific research on the vital importance of social interaction for brain morphology and function in combination with the insights into the damaging effects of social isolation and environmental deprivation for the brain, mind, and behavior could reinvigorate challenges to solitary confinement.

While more precise empirical answers are needed to fully comprehend the variety and extent of the implications of solitary confinement for the brain and behavior, yet existing evidence can provide additional empirical support to challenge the crux of solitary confinement: extreme isolation. As noted, the insights regarding the traumatic consequences of extreme isolation from the neurosciences align with those from various international bodies who have stressed that “all forms of solitary confinement without appropriate mental or physical stimulation are likely, in the long term, to have damaging effects.”

Based on these insights, the remainder of this article sets forth three main points for the argument that solitary confinement, as it currently stands in many jurisdictions, violates per se the Eighth Amendment ban on cruel and unusual punishments. First, the core feature of solitary confinement—extreme isolation or social and environmental deprivation—fails to meet the current conditions standard. Second, there is a manifest imbalance between the generalized traumatic and potentially permanent implications of social and environmental deprivation and the penological purposes of prison that solitary confinement is intended to serve. Furthermore, and more broadly, solitary confinement is antithetical to all justifications for punishment. Acknowledging that solitary confinement fails to meet any relevant Eighth Amendment requirement implies that solitary confinement is innately unconstitutional.

FAILURE TO MEET CURRENT CONDITIONS STANDARD

The body of neuroscientific research on the effects of socio-environmental deprivation on the brain presents a strong empirical premise for the normative argument that socio-environmental deprivation (or extreme isolation)—the crux of solitary confinement—qualifies as an Eighth Amendment violation under all prongs of the current conditions standard. This section discusses them in turn.

Social interaction and environmental stimulation as basic human needs

Consistent with evolutionary perspectives, neuroscientific research has provided a compelling argument for qualifying social interaction as a basic human survival need on par with other identifiable physical needs, such as water, or food, or shelter. As discussed, social interaction is just inherent to the nature of humans, who are fundamentally social beings. Such inherence emerges from the mutual and ineradicable relationship between the brain and the social environment. Furthermore, the neurobiological need for social interaction encompasses and is complemented by the need for environmental stimulation. As discussed, environmental stimulation significantly contributes to brain development and behavior, and the human brain must constantly receive a variety of sensory inputs from the external environment in order to function properly. Overall, the evidence above discussed indicates that social interaction and environmental stimulation are “but for” conditions for physiological brain function. As such, depriving human beings of social contact and environmental stimulation is equivalent to depriving them of their very own nature.

Acknowledging the vital importance of social interaction in enriched environments implies that forcing individuals into isolation in tiny, environmentally poor cells is sufficient per se to deprive them of basic human needs. Accordingly, single material conditions of solitary confinement (eg the lack of heating, proper bedding, or winter clothing) should be viewed as circumstances that aggravate and are therefore parasitic to an underlying condition—extreme isolation—that is alone sufficient to constitute a serious deprivation of basic human needs.

Importantly, including social interaction and environmental stimulation in the range of basic human needs also impugns the substantial equivalence by the Courts between normal confinement and solitary confinement. As reported, Courts have endorsed the view that solitary confinement is legitimate as long as its conditions, such as the provision of nutrition and shelter, are not materially different from those that affect the general prison population. Thus, solitary confinement is not cruel and unusual as long as it guarantees the same basic human needs that are ensured to the general prison population. However, such equivalence fails to consider that extreme isolation is the condition that renders the two types of confinement materially different. This difference emerges precisely from the fact that solitary confinement deprives individuals of a survival need that normal confinement guarantees. Considering this fundamental distinguishing aspect and the consequences that it entails, normal and solitary confinement cannot at all be placed on the same level. Rather, the evaluation of solitary confinement should be based upon its own criteria, which should systematically recognize social interaction as a fundamental need rather than a mere privilege.

Socio-environmental deprivation (extreme isolation) entails an objectively serious risk of physical harm

If the vital role of social interaction and environmental stimulation for human brain and behavior is not sufficient to establish them as basic physical needs, evidence of risks that socio-environmental deprivation imposes on the brain add ample weight and encourage a reconsideration of the “substantial risk of serious harm” requirement in relation to solitary confinement.

As discussed, the brain changes or deteriorations that follow socio-environmental deprivation appear to underpin a number of adverse cognitive, affective, and behavioral patterns, and they have also been reported in major psychiatric disorders, including depression and schizophrenia. These findings support and corroborate the existing robust body of psychological studies that have documented the dramatic psychological and psychiatric effects of solitary confinement. Moreover, the brain and psychological damages due to socio-environmental deprivation have been found to contribute to physical health problems and even increase the risk of mortality. From this perspective, the disfiguring damage that solitary confinement could impose on prisoners can be long-lasting or even permanent.

Of equal importance are insights into the nature and the implication of the social pain that is caused by social isolation. Besides indicating that social pain has physical reality, neuroscientific research has crucially suggested that the experience of social pain can be far worse than that of physical pain in many respects. Social pain has been linked to a series of psychological symptoms, including humiliation, low self-esteem, maladaptive action tendencies, including aggression, and lower levels of physical and mental health, especially in the long term. Thus, even if the traumatic effects of social pain are not immediately visible, they may manifest and grow over time.

By translating neuroscientific insights into the language of conditions jurisprudence, one may make the following observations. First, socio-environmental deprivation does entail an objectively serious risk of physical harm that is on par of food or sleep deprivation. Even if the harm that solitary confinement imposes on the brain translates into mental deterioration, and is therefore mental, it is also undeniable that “the type of severe psychological deterioration observed in solitary confinement is due to physical harms imposed on the brain.” As such, it is ultimately physical.

Second, the harm that solitary confinement imposes on the brain underpins a number of long-lasting or potentially permanent mental, physical, and physiological conditions. Therefore, the possible harms of solitary confinement are not only disfiguring but also potentially permanent. Last, and perhaps most importantly, the risk of such physical harms may manifest even after a short period of extreme isolation. As mentioned, (neuro) science has not yet determined with sufficient precision how long an individual can spend in isolation without undergoing irreversible brain damage. However, there is a consensus across scientific disciplines (including neuroscience) that the amount of time that an individual spends in socio-environmentally deprived conditions positively correlates to the degree of risk that he or she will deteriorate neurologically, physiologically, psychologically, and physically.

Admittedly, not all individuals will necessarily and inevitably suffer irreversible damages, and not everybody will contend the same kinds of traumas after the same amount of time. However, as Bennion has correctly noted, “[t] he fact that serious risks may never materialize in serious harm (or that harm may not be imminent) is not dispositive for . . . the test.” Furthermore, the risk of undergoing serious brain and mental deterioration following solitary confinement is universal: any person is vulnerable to such risk, regardless of his or her history of mental illness.

In view of the above insights, solitary confinement alone also meets the “substantial risk of serious (physical) harm” requirement of the objective prong of the conditions standard. By depriving individuals of a minimal life necessity, solitary confinement per se risks inflicting an unnecessary suffering that is characterized by disfiguring and potentially permanent consequences. As the Court has repeatedly stated, the Eighth Amendment interpretation changes in tandem with the knowledge and standards of decency of an evolving society. A punishment that risks inflicting disfiguring and potentially permanent damages upon individuals exceeds contemporary standards of decency, and no civilized society should tolerate the infliction of such a toll upon human beings.

Deliberate indifference follows from extreme isolation

As noted above, the subjective prong of the conditions standard has been subject to scholarly criticism, especially in solitary confinement cases. It can be extremely difficult to prove that prison personnel or administrators were deliberately indifferent to the harms that were inflicted upon prisoners by a serious deprivation of basic human needs. Such challenging proof may be an obstacle to the success of legitimate Eighth Amendment claims that are based on deleterious conditions of solitary confinement.

Courts have admitted that when the risk of serious harm that is endured from a confinement condition is objective and generally known, such objective proof is also sufficient to infer the culpable state of mind of prison personnel. Regarding solitary confinement, several Courts opinions have called into questions the necessity of an explicit proof of deliberate indifference on the grounds that placing prisoners in solitary confinement poses a substantial risk of serious harm. For instance, the court in Wilkerson noticed that “basic common sense indicates that ‘lack of exercise, social isolation, and/or stress are associated with [deleterious] conditions’. . . [Therefore, a] court ‘may infer the existence of this subjective state of mind [ie deliberate indifference] from the fact that the risk of harm is obvious’.” Likewise, opinions in Supreme Court cases have stressed the growing awareness of the damages of solitary confinement in modern American penal systems. Such damages have been documented at length and acknowledged by scientific, legal, and international sources.

Furthermore, several authors have supported a presumption of culpability of prison officials in injunctive cases. For instance, it has been suggested that “prisoners could certainly show by the time of trial that authorities were aware of either the actual harm or risk of harm caused by solitary confinement.” Thus, when harmful conditions are allowed to persist, Courts may infer the culpable mindset of prison officials from the conditions themselves without also requiring an explicit proof of mindset.

The thesis of this article further integrates and reinforces these claims. When acknowledging that the core condition of solitary confinement, namely extreme isolation, amounts per se to a wanton and unnecessary infliction of pain and constitutes cruel and unusual punishment, the subjective prong of the test loses its raison d’être and becomes superfluous. Given the growing general awareness of the objective damages linked with solitary confinement, proof of socio-environmental deprivation is sufficient to infer that prison officials acted with deliberate indifference, as extremely isolating a prisoner is essentially depriving him or her of a basic human need and entails an objectively serious and well-known risk of harm. Therefore, a fact finder could conclude that by keeping a prisoner is solitary confinement in spite of the obvious health risks, both physical and psychological, the prison staff acted with deliberate indifference to the substantial risk of consequent harm.

FAILURE TO MEET THE INTENDED PENOLOGICAL AIMS

The above evidence of the generalized consequences of solitary confinement also upsets the alleged balance between the “pains” of solitary confinement and the legitimate penological prison interests of discipline, security, and safety. This “newly” emerging imbalance derives from the fact that socio-environmental deprivation, especially when prolonged, risks precipitating severe brain deteriorations, even in individuals without a history of mental illness. Such deteriorations may not be limited to the stay in isolation, but given the long-lasting psychological consequences that they entail, the effects of such deteriorations risk continuing upon the reintroduction of an individual into a social environment, whether it is the prison or the general community. The risk of undergoing brain damage due to extreme isolation is an excessive—and, therefore, extremely unbalanced—cost for any legitimate penological interest to allegedly justify it.

These claims mutually reinforce the robust body of evidence documenting that neither short-term nor long-term stays in solitary confinement achieve specific deterrent effects by reducing subsequent disciplinary infractions or prison incidents. Rather, evidence shows that stays in solitary confinement appear to produce the opposite effect. Moreover, jurisdictions that have restricted the use of solitary confinement have witnessed a decrease in prison violence. Thus, limiting the use of solitary confinement does not undermine the capacity of prison administrators to control the prison population or maintain safety and may actually increase it.

Acknowledging these claims may prompt the Courts to reconsider their (often excessive) attitude of deference to prison administrations in regard to the management and the application of solitary confinement regimes. Specifically, it may prompt the Courts to carefully scrutinize the “legitimate penological justifications” that prison administrations cite to defend their application of solitary confinement. Thereby, it could give full breath to the constitutional protection of people in custody that lies at the core of the Eighth Amendement.

From a broader perspective, the evaluation of the penological justifications for a given prison condition or correctional practice under the Eighth Amendment needs to consider the progress of knowledge as it marks the evolution of society and of its standards of decency. Presently, there is a general consensus among domestic and international bodies that disfavors solitary confinement, which suggests that standards of decency have evolved away from the use of solitary confinement to serve the intended penological purposes. Increased knowledge also reflects (the reasons for) the higher effectiveness of less restrictive and less painful methods to serve identical penological purposes. Thus, no penological interest may justify the systematic and indiscriminate use of solitary confinement. Moreover, no penological interest can counterbalance the damages that solitary confinement risks imposing on incarcerated people. Admittedly, solitary confinement may still be warranted in those instances that require an individual’s temporary protection or for the most serious, violent offenses or infractions, though only when other measures have been tried without satisfactory results. Even in such instances, the separation of an individual from the rest of the prison community can still be handled in a more humane and less restrictive way.

THE ANTITHESIS BETWEEN SOLITARY CONFINEMENT AND THE GOALS OF PUNISHMENT

Solitary confinement and its effects are also incompatible with the retributive, incapacitative, deterrent, and rehabilitative goals of punishment. As such, it lacks any penological significance. Although this broader penological perspective is uncommon in Eighth Amendment analyses in (solitary) confinement cases, an elaboration of why solitary confinement is antithetical to each dominant justification for punishment can still offer scholarly value.

Beginning with retribution, retribution-based analyses generally encompass two components. The first, which is objective, evaluates a punishment on the basis of the seriousness of the crime that was committed, whereas the second, which is subjective, evaluates a punishment in view of the degree of blameworthiness of the perpetrator. Blameworthiness evaluations also encompass the individual characteristics of a perpetrator, including his or her age or mental capabilities. Therefore, from a retributive perspective, a punishment is disproportionate when it is excessively severe relative to the crime and the perpetrator’s overall degree of blameworthiness and, hence, culpability.

For the aims of this article, I measure solitary confinement against another critical aspect of retributive theory: the preservation and respect for the moral rationality of perpetrators. The premise of moral rationality is undeniably central to any retributive punishment. Retribution presupposes that the perpetrator is a rational moral agent who is capable of understanding the meaning and the consequences of his or her actions and freely chooses to act unlawfully. Based on this presupposition, retributive punishment aims to ensure that perpetrators are “capable of understanding the wrongs they have committed and the fairness of the penal sanctions imposed on them by the state in response to those wrong.” Accordingly, retributivism insists on structuring legal punishment, so that it is, at minimum, consistent with treating offenders as rational moral beings.

Retributivism requires that incarceration deprives perpetrators of their freedoms by drastically diminishing their privileges to live autonomous lives. However, retribution does not require that incarceration also erodes the capacities that constitute moral personhood, such as “physical and psychological health, work and interaction with others.” From a retributive perspective, these capacities and dispositions need to be regularly exercised to preserve the ability of prisoners “to comprehend and respond constructively to the reasons for which they are being punished.”

From this line of reasoning, solitary confinement does not comport with this fundamental aspect of retributive punishment. Solitary confinement risks imposing traumatic brain and mental damages on prisoners, all of which compromise the cognitive and affective abilities that support practical reasoning skills, and “cause further atrophy of what may have already been weak capacities to identify with and feel for others.” Furthermore, the long-lasting or even permanent physiological, mental, and physical damages that solitary confinement may comport can protract even after a prisoner has served his or her sentence. Therefore, solitary confinement, which can inflict long-lasting or even permanent losses on perpetrators, renders a prison sentence just disproportional with the seriousness of the crimes that were committed. Such an outcome is simply antithetical to any mainstream retributive perspective.

Solitary confinement also fails to meet consequentialist purposes of punishment, ie incapacitation, deterrence, and rehabilitation. Incapacitation refers to the ways in which punishment, and especially incarceration, neutralizes the likelihood that perpetrators may commit further offences by physically removing them from society. Solitary confinement, especially in supermax facilities, serves precisely this purpose during the period of confinement. However, the benefit of this incapacitation argument for public safety requires an additional analysis of the specific deterrent effects of solitary confinement.

Theories concerning the use of solitary confinement emphasize its potential to deter future crime. However, empirical evidence disavows the effectiveness of solitary confinement as a tool to deter recidivism or change the behavior of prisoners. There is evidence that prisoners in solitary confinement at supermax prisons fare even worse than prisoners in the general population once they are released. For instance, an epidemiological study by Maers and Bales compared the rates of recidivism among individuals who had been in solitary confinement with those of individuals who had been normally confined. They found that solitary confinement was associated with a higher risk that formerly incarcerated individuals would commit a violent crime after being released. Other epidemiological studies have replicated this finding. The reasons for the increased risk of recidivism also originate largely from the brain alterations due to solitary confinement, which have been associated with adverse psychological symptoms and mental health issues that are known risk factors for socially dysfunctional behaviors, including antisocial conduct.

Last but not least, solitary confinement does not serve the rehabilitative ideal of punishment. (Social) rehabilitation clearly aims to reintegrate convicted persons into society upon their release so that they can lead a law-abiding and self-supporting life. Thus, it seeks to reestablish positive relationships between perpetrators and the rest of society by facilitating (self-)reform and change that is based on relational processes. Rehabilitation crucially promotes as much as inclusiveness and positive social engagement as possible while perpetrators serve their sentence, as this can facilitate their social reintegration into the community.

In addition to opposing the underlying values and aims of rehabilitation theory, the possible harms of solitary confinement, including a greater predisposition to aggression and other maladaptive psychological and behavioral patterns, may seriously compromise an individual’s social functioning. Therefore, these harms seriously compromise the rehabilitation and resocialization process and render it more difficult, if not nearly impossible in some cases.

To conclude, the type and the extent of harm that solitary confinement can inflict on individuals do not meet and are therefore disproportionate with any penological justification. In view of this, solitary confinement constitutes an unnecessary and wanton infliction of pain because it not only deprives individuals of their basic socio-environmental biological needs but also lacks any kind of penological justification. The suffering that solitary confinement imposes is unnecessary and runs afoul of any relevant perspective under the Eighth Amendment. No penological interest or aim can justify its infliction; solitary confinement is in and of itself cruel and unusual punishment.

A PATH FORWARD: ABOLISHING SOLITUDE IN PRISON

The arguments illustrated within this article ultimately lend support to the conclusion that solitary confinement, as it is still administered in a number of facilities or penal systems, should be dismissed altogether. Such conclusion is in line with the wide array of domestic and international organizations, movements, and associations that have called for abolishing solitary confinement or at least restricting its use to exceptional and strictly regulated circumstances.

The separation of a prisoner from the rest of the prison population should always be a last resort intervention to manage extreme instances—which must be duly recorded by the prison personnel and possibly oversought by specialized committees—only when is absolutely necessary to achieve legitimate penological goals. In such cases, the separation of an individual from the rest of the prison community should be subject to strict temporal, social, and environmental standards. These (possibly uniform) standards are needed to contrast most arbitrarily employed forms of solitary confinement as well as a constitutional infirmity that permits prison administrations to use solitary confinement with scarce judicial oversight.

Regarding time limits, the ASCA-Liman survey reported time intervals ranging from between and days to more than six years over jurisdictions. Although fewer number of people were kept in solitary for − days, higher percentages were reported for periods in solitary of at least one month to over six years.

More empirical research is needed to assess the exact maximum time limit for depriving an individual of constant social contact without undergoing irreversible damage; nonetheless, acknowledging that such deprivation risks precipitating or aggravating physical, physiological, and psychological adverse effects even after just a few days constitutes sufficient grounds for the adoption of uniform maximum time limits that match existing empirical knowledge as well as domestic and international guidelines. Given the current paucity of jurisprudence on duration limits for solitary confinement, the strength of international and domestic guidelines mandating a maximum of days of solitary confinement should be used as a benchmark to set uniform time standards in all jurisdictions. All states should abide to these standards, any violation constituting an Eighth Amendment violation.

In addition to setting uniform time limits on solitary confinement, uniform sociability standards are also warranted. The ASCA-Liman survey has further reported positive data from a number of jurisdictions that have enacted specific policies in recent years to restrict the use of solitary confinement to the most objectively serious cases in order to improve the “social” conditions of people who are housed in solitary cells. Several jurisdictions have implemented policies that allow for more time out of the cell, outdoor recreation activities, classes, job training, rehabilitation, and re-entry programs for restricted individuals. However, only a few of them have increased time for visitors. Some policies even offer training for correctional officers to learn alternative responses to prison violence that hinge on dialogue, accountability, and cooperation. Notably, statistics reflect that prison incidents and the overall rate of recidivism upon re-entry to the community have both decreased. These sparse changes are encouraging and illustrate a growing acknowledgment that solitary confinement is counterproductive and can be extremely damaging. Ensuring that all correctional facilities adopt and apply sociability standards—including recreation, education, rehabilitation programs, and visiting hours with significant others—for prisoners who are temporarily separated from the rest of the community is critical to counteract the side effects of isolation as well as aid in their social rehabilitation and re-entry process.

Finally, although this suggestion applies to correctional facilities in general, the design of separation cells should follow strict environmental standards. On several occasions, the Court stressed that “the Constitution does not mandate comfortable prisons.” However, it also stated that the Constitution “neither does. . . permit inhumane ones.” The empirical studies reported above indicate that environmental surroundings—whether enriched or deprived—significantly influence brain structure and function as well as psychological well-being and social behavior. Tiny and environmentally scarce cells risk exacerbating the negative effects of a lack of social interaction.

Several authors have called for making correctional facilities as humanized and home-like as possible. Positive international examples indicate that home-like cells with natural light, even in maximum security facilities, where prisoners are afforded amenities such as proper bedding, furniture, or reading materials, contribute to prisoners’ physical and psychosocial well-being. Such generalized well-being has been found to positively contribute to reduced institutional misconduct and overall recidivism.

It is admittedly difficult to expect such a dramatic change in U.S. facilities in the immediate future. Nevertheless, it is imperative to acknowledge that such realities exist and are effective. Most importantly, those realities convey an important lesson of “dignity and humanity that is the birthright of every person, and . . . respect [for] the collective dignity and humanity of society.” These are the values and rights that animate the Eighth Amendment, and should accordingly animate the abolition of solitary confinement.

CONCLUSION

In the opening paragraph of her dissenting opinion in Apodaka, Justice Sotomayor wrote, “A punishment need not leave physical scars to be cruel and unusual.” However, socio-environmental deprivation can apparently leave too many scars, which may be visible and tangible. Solitary confinement is a disfiguring and dehumanizing punishment, as it deprives people of their biological needs, it drastically changes their physiology, and causes severe psychological and physical harm. It is increasingly an appropriate time to resolve the many, potentially incurable scars that solitary confinement may inflict on incarcerated people. Continuing to ignore these scars can only render them even more profound.

INTRODUCTION

Solitary confinement in the United States is a topic with a complex history. Reports, legal writings, psychological studies, and news stories have described many situations where people in prison were kept in extreme isolation for long periods, sometimes indefinitely. They often had little social contact, mainly with prison guards, and sometimes lived in poor conditions. While these situations exist in many correctional facilities, solitary confinement is also seen as a legitimate tool for maintaining order, security, and safety within prisons.

There are no consistent rules or practices for solitary confinement across states. Instead, individual prison systems in each state largely decide their own policies. This lack of consistent rules has sometimes led to misuse of solitary confinement, sparking national and international efforts to either end or significantly change the practice in the U.S. These efforts have resulted in some reforms in certain areas, as well as recommendations and guidelines from the Department of Justice and national groups. These guidelines suggest limiting solitary confinement, for example, by setting maximum time limits or banning its use for vulnerable groups like people with mental disabilities and young individuals.

However, progress in restricting or improving solitary confinement practices has been slow and inconsistent. A report from the American State Correctional Association and Liman Center (ASCA-Liman) shows that while the number of people in isolation has decreased in some states, it has increased in others.

In addition to inconsistent standards, the legal interpretation of solitary confinement under the Eighth Amendment, which prohibits cruel and unusual punishment, has been narrow. The Supreme Court has ruled that prison conditions, including solitary confinement, are cruel and unusual if they cause "unnecessary and wanton infliction of pain" on incarcerated individuals. This means the conditions must deprive people of "basic identifiable human needs" to the point of causing harm or a "substantial risk of serious harm," and prison staff must act with "deliberate indifference." Courts also consider a state's "legitimate penological interest" when evaluating prison conditions, though this is not an explicit legal requirement.

Regarding solitary confinement specifically, courts, including the Supreme Court, have generally applied a narrow interpretation. They often have not fully acknowledged the general mental suffering caused by social isolation in deprived cells. As a result, the length of time spent in solitary confinement has often not been considered a separate factor in determining its constitutionality. This approach often overlooks the core difference between solitary confinement and regular imprisonment: extreme isolation, also known as social and environmental deprivation.

Recently, a new approach has emerged to challenge solitary confinement, drawing on insights from social neuroscience. This field examines the traumatic and potentially lasting effects of social and environmental deprivation on the brain. Research in social neuroscience suggests that social interaction in stimulating environments is crucial for healthy brain function and mental well-being. Studies have revealed various brain changes that can occur even after a short period of social and environmental deprivation. These changes have been linked to several potentially irreversible mental health conditions. Furthermore, many mental conditions associated with these brain changes due to isolation in deprived environments are connected to an increased risk of harmful behaviors and social difficulties, including aggression. Another important finding from this research is the physical nature of the pain caused by social isolation.

Neuroscientific findings on the damaging effects of social and environmental deprivation support and strengthen existing research on the negative psychological impacts of solitary confinement. These findings also offer new arguments against solitary confinement. First, they support the idea that solitary confinement, by its nature, deprives individuals of basic human needs, specifically social interaction and environmental stimulation. Second, they show that physical brain changes can occur within days of isolation in a deprived setting. Third, the resulting mental health and behavioral problems could continue even after a person returns to a social environment, potentially affecting their long-term social functioning. Based on these insights, this article argues that solitary confinement is inherently cruel and unusual under all aspects of the current legal standard for prison conditions. It also suggests ways to fundamentally rethink solitary confinement practices.

The article proceeds as follows: The next section, Part I, briefly analyzes legal rulings on prison conditions to show the current legal status of solitary confinement. Part II then discusses how these rulings have largely ignored the general mental suffering caused by extreme isolation. Part III addresses the common oversight of the duration of extreme isolation as a separate factor in constitutional reviews under the Eighth Amendment. Part IV reviews neuroscientific research on social and environmental deprivation. This includes analyzing studies on the necessity of social interaction and environmental stimulation for healthy brain function and mental health (Part IV.A), and then examining research on the traumatic effects of social isolation and environmental deprivation on the brain, mental and physical health, and social behavior, as well as the physical nature of social pain (Part IV.B and IV.C). Following this, Part V uses these neuroscientific insights to propose several challenges to solitary confinement. Specifically, this part argues that solitary confinement, by its nature, fails to meet the current conditions standard in three main ways: it deprives individuals of basic human needs (social interaction and environmental stimulation); it can cause serious and potentially permanent brain damage even in healthy individuals; and the risks of such damage are too high compared to the prison's interests in discipline, security, and safety. Part VI further argues, from a broader academic perspective, that solitary confinement and its risks are also inconsistent with the reasons for punishment, such as retribution, incapacitation, deterrence, and rehabilitation. Given these arguments, the article maintains that solitary confinement is inherently cruel and unusual punishment from every perspective relevant to the Eighth Amendment. Part VII concludes with a proposal to eliminate extreme isolation in prisons and advocates for a fundamental rethinking of solitary confinement practices under strict, and possibly uniform, rules regarding time limits, social contact, and environmental conditions.

SOLITARY CONFINEMENT IN “CONDITIONS JURISPRUDENCE”

The history of solitary confinement has been well-documented in existing literature. Many studies have also thoroughly analyzed the origins and legal evolution of the Eighth Amendment. While this article does not review all past interpretations, it focuses on specific aspects of legal rulings on prison conditions and their application to solitary confinement. These aspects form the basis for the arguments presented later in Part V.

Courts have not provided a final definition of "cruel and unusual punishments." However, over time, the Supreme Court has developed two ways to define the limits of cruel and unusual punishment. The first method, which usually applies to punishments formally ordered by courts or outlined in laws, assesses whether the punishment is proportionate to the seriousness of the crime. A punishment is considered cruel and unusual if its "excessive length or severity" is significantly out of proportion to the offense. This judgment must consider the "evolving standard of decency that marks the progress of a maturing society."

The second method, which typically applies to how people are treated in prison, including their living conditions, assesses whether the "punishment" involves an "unnecessary and wanton infliction of pain." To determine if prison treatment or conditions cause unnecessary and wanton pain, the standard requires them to result in clear and "serious deprivations of basic human needs." These deprivations must be severe enough to cause harm or create a "substantial risk of harm" that is objectively serious (the "objective prong"). The standard also requires prison officials to be "deliberately indifferent" to the fact that such treatment or condition causes or risks causing serious harm to the individual (the "subjective prong"). Furthermore, a punishment, including the treatment and living conditions of prisoners, results in unnecessary and wanton pain if it goes beyond what is needed to achieve a legitimate prison goal, even if applied for such a goal. The ultimate measure for the "unnecessary and wanton infliction of pain" standard also relies on the evolving understanding of decency in society.

Despite these standards, solitary confinement itself is not considered inherently cruel and unusual punishment. However, solitary confinement "becomes" cruel and unusual if its accompanying physical conditions cause wanton or unnecessary pain based on the criteria set by the Court. Historically, courts have tended to interpret and apply the conditions standard narrowly when it comes to solitary confinement. This approach has drawn criticism from legal scholars who argue that courts have been "underinclusive" in their handling of solitary confinement cases. Specifically, courts have often downplayed the general mental suffering caused by extreme isolation. As a result, they have frequently ignored the length of solitary confinement as an independent factor in constitutional review. The following section will discuss each of these points in detail.

SOLITARY CONFINEMENT AND THE OBJECTIVE PRONG OF THE CONDITIONS STANDARD

The narrow way courts apply the conditions standard to solitary confinement cases first comes from how they interpret "basic human need." The Supreme Court has generally stated that constitutional protections for prison conditions after a conviction are based on the idea that "prisoners retain the essence of human dignity inherent in all persons" and that by imprisoning them, "society takes from prisoners the means to provide for their own needs." Therefore, "a prison that deprives prisoners of basic sustenance... is incompatible with the concept of human dignity and has no place in civilized society."

Federal courts have not consistently or thoroughly defined "basic human need." Generally, courts have understood "basic human needs" to mean specific and identifiable minimum necessities for life, such as food, water, shelter, exercise, medical care, and sanitation. So, the main understanding of "basic human need" mostly relates to specific "physical needs" considered essential for survival. The Supreme Court has also ruled that only "extreme deprivations" are enough to support a claim about prison conditions. This means the deprivation must be serious enough to deny "the minimal civilized measure of life’s necessities."

The requirement of an extreme deprivation of a specific, identifiable basic human need has greatly limited the ability to challenge solitary confinement based on its general conditions. With few exceptions, if there is no proof that a person in extreme isolation was deprived of a necessary means of survival, then harsh or restrictive solitary confinement conditions are not considered severe enough to be an unnecessary and wanton infliction of pain.

The standard for successfully meeting the objective prong of the conditions test is even higher due to the requirement that the deprivation of basic human needs must either cause or create "a substantial risk of serious harm." This requirement is judged by "whether society considers the risk... to be so grave that it violates contemporary standards of decency to expose anyone unwillingly to such a risk."

Courts have been unclear about what type of harm—physical or psychological—must be (potentially) suffered to meet this standard. However, some legal experts have noted that courts tend to view "serious harm" primarily as "physical" harm. This understanding is based on the idea that objectively serious harm must result from a serious deprivation of specific basic human needs. As mentioned earlier, these have generally been understood to include physical needs like food, water, medical care, shelter, or sanitation. The lack of these physical needs leads to harms—such as starvation, thirst, or diseases from poor hygiene—that are fundamentally physical.

The exception to the general interpretation of "objectively serious harm" as mainly physical harm is seen in cases where the solitary confinement of people with mental disabilities was found unconstitutional. This exception is based on the idea that mental illness makes people more vulnerable to the harmful effects of extreme isolation. A key case in this area is Madrid v. Gomez, where the federal district court compared placing mentally ill individuals in solitary confinement to "putting an asthmatic in a place with little air to breathe." Although the court recognized that long-term isolation in scarce environments risks causing significant psychological trauma in incarcerated people without a history of mental illness, it ruled that "for many inmates, it does not appear that the degree of mental injury suffered significantly exceeds the kind of generalized psychological pain that courts have found compatible with Eighth Amendment standards." By assuming the general prison population's resilience to the harms of extreme isolation, the court essentially upheld that extreme isolation does not pose such a significant risk of serious psychological injury for all prisoners in solitary confinement. Therefore, solitary confinement is not considered a "per se" (inherent) Eighth Amendment violation.

Cases like Madrid represent important progress in legal rulings on solitary confinement. However, they also confirm the continued neglect of general mental harm or pain caused by extreme isolation among the healthy prison population. By distinguishing the risks of solitary confinement for mentally ill individuals from the general risk of psychological harm for others, courts have failed to recognize that solitary confinement inherently poses dangerous psychological risks for anyone forced into isolation in deprived environments. This failure shows a significant underestimation of the devastating mental effects that extreme isolation can cause in any individual.

SOLITARY CONFINEMENT AND THE SUBJECTIVE PRONG OF THE CONDITIONS STANDARD

In the cases of Estelle and Wilson, the Supreme Court ruled that claims under the Eighth Amendment regarding prison conditions that are not formally part of a sentence also require proof of a subjective element. This means proving "deliberate indifference" by prison officials to a prisoner's health or safety. The "deliberate indifference" aspect of the conditions standard generally requires that a state official "knows of and disregards an excessive risk to inmate health or safety." Therefore, "the official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference." In essence, "an official’s failure to alleviate a significant risk that he should have perceived but did not... cannot under our cases be condemned as the infliction of punishment" in violation of the Eighth Amendment.

In the Farmer case, the Court clarified that deliberate indifference is similar to criminal law's concept of subjective recklessness. This means the subjective part of the conditions standard refers to the official's blameworthy state of mind and requires proof that correctional officials knew about and ignored a significant risk to an individual's health and safety. While this test is specific to each case and prison official, the Court in Farmer also acknowledged that some risks of harm are so clear that "a fact finder may conclude that a prison official knew of a substantial risk from the very fact that the risk was obvious." Therefore, proof of an official's awareness or disregard can also come from circumstantial evidence showing that the risk was clearly and widely known to be ignored.

The deliberate indifference test has faced criticism from scholars. Arguments include that this subjective element can make it difficult to successfully challenge objectively harmful solitary confinement conditions, as it is often hard to prove in solitary confinement lawsuits. This difficulty is especially clear in cases requiring proof of prison officials' deliberate indifference to the mental harm (or risk of harm) caused by solitary confinement, particularly for individuals with mental illness. Prison officials are not trained in mental health and may not know the symptoms or risks of a mental condition. Thus, they might avoid responsibility by simply claiming they were not actually aware of a mental health need. As a result, prisoners reporting significant mental harm "face a tougher burden in proving [prison officials'] actual knowledge than their physically ill counterparts." It is acknowledged that physical conditions are more easily recognized by a non-expert, and knowledge of them is easier to prove in court.

Given the difficulty of proving deliberate indifference, several authors have called for reconsidering or even removing the subjective part of the conditions test, focusing instead only on the objective conditions of confinement. Importantly, specifically regarding solitary confinement, some authors have highlighted that the condition of extreme isolation alone should be enough to assume deliberate indifference to the health and safety of the person forced into solitary confinement.

PENOLOGICAL INTERESTS

While not an explicit part of the test for prison conditions, the Supreme Court has stated that a factor to consider when judging if a prison condition is constitutional is the state's "legitimate penological interest" in keeping a prisoner in that condition. This means that when evaluating whether prison conditions deprive individuals of basic human needs and risk serious harm, the severity of the harm (or risk of harm) to an inmate is weighed against the prison's legitimate needs for discipline, security, and safety. Furthermore, the existence of a legitimate prison interest can influence whether prison officials are found to be deliberately indifferent to the inmate's protected interests.

Regarding solitary confinement, policymakers and correctional officials widely believe that its use is an effective strategy to improve safety and order throughout the prison system by reducing criminal activity and prison violence. Therefore, the supposed necessity and effectiveness of solitary confinement in protecting prison interests are believed to outweigh its negative impact on prisoners held in isolation. This creates an implicit trade-off: the negative impact of solitary confinement on prisoners—such as the loss of social interaction—is balanced against the benefits for the prison, namely discipline, security, and safety. Thus, the potential "benefits" of solitary confinement for the individual inmate, other inmates, and prison staff are seen as neutralizing the harm associated with stays in extreme isolation.

This balancing argument is indirectly supported by courts' tendency to defer to prison administrators and officials in managing solitary confinement. Lacking clear criteria to assess the legitimacy of a prison's interest in a specific condition like solitary confinement, courts have often "defer[red] to prison officials when they claim that a particular condition or treatment is necessary." In fact, courts have openly acknowledged that prison administrators and officials are more competent than courts in operating prisons and understanding their dynamics. These arguments suggest that prison administrators and officials, rather than judges, have the most accurate understanding of available resources, know best which individuals need these resources, and are most capable of tracking prisoners' evolving treatment needs. Moreover, they possess the right expertise in managing safety and protection needs that may arise in a prison setting.

This deference from courts has been especially common in solitary confinement lawsuits. In many such cases, even if there was a factual question about whether solitary confinement conditions posed a serious risk of substantial harm violating the Eighth Amendment, prison administration successfully argued a legitimate prison interest in keeping a prisoner in isolated confinement. For example, in Scarver v. Litscher, the Seventh Circuit recognized that the plaintiff suffered mental distress from being in supermax confinement, noting that he repeatedly banged his head against the cell wall. Although the court found this situation concerning, it showed unwillingness to interfere with correctional management of dangerous inmates, stating that "[p]rison authorities must be given considerable latitude in the design of measures for controlling homicidal maniacs without exacerbating their manias beyond what is necessary for security. It is a delicate balance."

According to Glidden and Rovner, while courts do not always express their opinions so openly, "a similar underlying sentiment is regularly present in such cases, and may be influencing the decision even absent any explicit language." Furthermore, these and other authors have observed that prison officials are not required to thoroughly justify the specific conditions that accompany solitary confinement. Rather, general claims of safety and security often suffice as a legitimate prison interest for holding a prisoner in isolation. For instance, as Hafemeister and George have noted, a common justification prison officials have used to defend the harsh practices of supermax facilities is that "they house the ‘worst of the worst’; the violent, dangerous inmates who simply cannot be housed anywhere else." Such claims—and courts' deference to them—are frequent in Eighth Amendment analyses and have often led to a lack of careful examination of the actual conditions of solitary confinement. Thus, even though the Supreme Court stated that the "touchstone" of evaluating prison conditions for prison purposes "is the effect upon the imprisoned" and that giving "deference to the findings of state prison officials in the context of the Eighth Amendment would reduce that provision to a nullity in precisely the context where it is most necessary," there is indeed a risk that the legitimate interests of prisons will take precedence over concerns about the negative consequences of harsh conditions, such as those of solitary confinement, for incarcerated individuals.

MENTAL PAIN IN EXTREME ISOLATION

Research has extensively documented the psychological effects of solitary confinement. Numerous psychological, psychiatric, and observational studies have carefully shown the many negative consequences of living in isolation in deprived environments for mental health, well-being, and behavior in both mentally ill and healthy people. Suicidal thoughts, depression, and problems with attention and memory are just a few examples of the mental suffering that people in extreme isolation can experience, especially during medium to long-term isolation and in particularly harsh settings. Beyond the most severe psychological effects, psychological research has also widely documented a link between social isolation and the experience of social pain, which involves "the painful feelings following social rejection or social loss." This research also notes a negative impact of social pain on physical and mental health and psychological well-being, including low self-esteem, humiliation, a feeling of meaninglessness, increased sensitivity to rejection, and increased aggression.

Although these studies have been widely reproduced and presented in courts many times, "lower courts have only rarely recognized grave mental harm in the context of confinement conditions, and the Supreme Court has never done so." Despite the evidence, courts have generally been unwilling to recognize that the mental harm caused by extreme isolation is, by itself, enough to violate the Eighth Amendment.

There are at least two main, related reasons why courts overlook the general mental suffering caused by solitary confinement. The first is a tendency to not consider social interaction a basic human need. As noted, courts tend to interpret the requirement of "deprivation of basic human needs" in terms of identifiable physical needs, such as water, food, or sanitation. Only in a few exceptional cases have lower courts recognized social interaction as a basic human need.

The second, and resulting, reason for this neglect is that although a lack of social interaction causes serious harm, "that harm is mental, not physical." According to Jules Lobel, U.S. law views mental harm, and mental pain, as "a second-class citizen" compared to physical harm and pain. In principle, U.S. law has endorsed a "dualistic presumption" of harm/pain, which sees physical and mental harm/pain as qualitatively and hierarchically different types of suffering—the former being more objective, tangible, and serious than the latter.

Regarding the specific connection of mental harm/pain to confinement conditions, Lobel has pointed to the Prison Litigation Reform Act (PLRA). This federal law was passed to reduce the number of prison lawsuits in the court system by requiring prisoners to first use all available administrative ways to resolve their issues. In doing so, the PLRA ultimately aimed to limit the power of federal courts in taking corrective action. In the part that outlines the requirements for filing a lawsuit, the PLRA states that physical injury is a prerequisite for requesting monetary compensation. Meanwhile, mental or emotional injury alone is not enough to support a federal civil action without evidence of physical injury.

The distinction between "physical injury versus mental and emotional pain" within the PLRA has limited the large number of lawsuits filed in federal courts over the years. Furthermore, this distinction has been reflected in cases challenging the mental anguish of solitary confinement. In fact, courts have often dismissed mental or emotional harm in the absence of proof of physical harm.

In conclusion, the general oversight of mental harm and pain resulting from extreme isolation is closely related to and stems from a tendency to downplay social interaction as a basic human need. Although the lack of social interaction causes serious mental pain, social interaction is considered a "mental need," not a physical one. Therefore, unlike food and water, it is not considered an essential precondition for human life.

Finally, by excluding social interaction from the range of important human needs that deserve constitutional protection, courts have essentially treated normal confinement and solitary confinement as the same. Based on several opinions, if the conditions of solitary confinement are largely and physically equivalent to those of normal confinement, then the Eighth Amendment is not involved. In such cases, neither social interaction nor the mental harm/pain resulting from its deprivation are considered worthy of constitutional protection.

DURATION OF EXTREME ISOLATION

The limited importance that legal rulings on prison conditions give to mental pain is connected to another critical aspect that Eighth Amendment analyses of solitary confinement have often overlooked: the duration of extreme isolation. As mentioned in the Introduction, solitary confinement practices vary from state to state. Therefore, there is no consistent standard that sets a maximum amount of time a person can spend in extreme isolation. While federal reports and national organizations have issued guidelines recommending maximum time limits for solitary confinement, these limits are largely left to the discretion of prison administrations. This discretion means that solitary confinement can be open-ended; specifically, it can last for a few days, an indefinite period, or even permanently.

The Supreme Court, as well as lower courts, have rarely addressed the length of solitary confinement as a separate factor in constitutional review under the Eighth Amendment. Instead, they have typically considered the length of solitary confinement as something to evaluate together with (and depending on) the accompanying physical conditions of extreme isolation. So, although courts have occasionally recognized that prolonged solitary confinement may be a relevant factor in determining if it violates the Eighth Amendment, this factor has not been treated as a standalone aspect of constitutional review.

Lower federal courts have been more willing to acknowledge the independent importance of duration—and its effects—as an element to assess separately from the physical conditions of solitary confinement. For example, in Sostre v. Rockefeller, the court extensively discussed the issue of duration. The district court attempted to set limits on the length of solitary confinement, stating that "to be constitutional, punitive segregation... must be limited to no more than fifteen days and may be imposed only for serious infractions of the rules." Similarly, in O’Brien v. Moriarty, the court observed that, when solitary confinement is "[i]mposed inappropriately, or for too long a period, even the permissible forms of solitary confinement might violate the Eighth Amendment."

Compared to lower courts, the Supreme Court has been more hesitant to recognize the independent constitutional importance of the duration of solitary confinement. Instead, it has been more inclined to view duration as dependent on the accompanying physical conditions of solitary confinement. This approach is clear in Hutto. In this case, the Court followed the reasoning of In re Medley, ruling that solitary confinement alone "is not necessarily unconstitutional, but it may be, depending on the duration of the confinement and (emphasis added) conditions thereof..." Hence, the Court then stated,

"[i]t is perfectly obvious that every decision to remove a particular inmate from general prison population for an indeterminate period could not be characterized as cruel and unusual. If new conditions of confinement are not materially different from those affecting other prisoners, a transfer for the duration of a prisoner’s sentence might be completely unobjectionable and well within the authority of the prison administrator."

As these and other passages show, the Court's opinion considers the duration of solitary confinement as part of the question of whether it meets constitutional requirements. However, it is only one of many factors to be included in that review. Thus, the length of solitary confinement is constitutionally problematic only when the accompanying physical conditions of solitary confinement fail to meet constitutional standards.

As observed, one reason why the duration of solitary confinement does not independently fall within the scope of constitutional analysis under the Eighth Amendment comes from the excessive deference courts give to individual prison administrations in deciding and applying solitary confinement rules. By adopting this hands-off approach, courts have largely left decisions about the length of solitary confinement to prison administrations. As noted, the reasoning for this is the administrations' greater ability to understand and address legitimate prison interests that may require longer periods of isolation.

Despite this long-standing judicial approach, broader Eighth Amendment concerns regarding long-term solitary confinement have recently re-emerged in lower courts as well as the Supreme Court. Over the past decade, several courts have concluded that the deprivations associated with long-term isolation do violate the Eighth Amendment. For instance, in Johnson v. Wetzel, the district court acknowledged the scientific claim that "psychological stressors such as isolation can be as clinically distressing as physical torture." Although the court did not challenge the constitutionality of solitary confinement itself, it found that the psychological deterioration a person suffers as a direct result of prolonged isolation (years in that specific case) is sufficient grounds for an Eighth Amendment violation.

In the same vein, Justice Kennedy’s concurring opinion in Davis v. Ayala acknowledged that extended solitary confinement raises serious constitutional questions regardless of its accompanying conditions. As such, the duration of solitary confinement alone should be subject to the Court’s constitutional review under the Eighth Amendment. Equally important is Justice Kennedy's criticism of the Court's excessive deference to prison administrations. Prison officials may "have discretion" to use solitary confinement as a "temporary" measure for protection or safety needs in prisons; however, this does not prevent courts from assessing "within [their] proper jurisdiction and authority" the appropriateness of long-term solitary confinement given its widely documented effects on prisoners, and as a result, "to determine whether workable alternative systems for long-term confinement exist, and, if so, whether a correctional system should be required to adopt them." Justice Kennedy further argued that the Court’s unwillingness to address the excessive length of solitary confinement as a specific constitutional issue is essentially an implicit acceptance of the negative effects that a long period of extreme isolation can have on confined individuals. Because the psychological consequences of solitary confinement have been widely established and have attracted general attention and concern, failing to address them amounts to an attitude of indifference.

More recently, in Apodaka v. Raemish and Lowe v. Raemish, Justice Sotomayor also expressed "deeply troubling concern" over the extreme mental pain caused by long-term isolation itself. Referencing Charles Dickens' account of the horrors of solitary confinement in Philadelphia's Eastern State Penitentiary, Justice Sotomayor emphasized Dickens' conclusion that, in those days, penal officers were unaware of the "immense amount of torture and agony which [solitary confinement] inflict[ed] upon the sufferers." However, as Justice Sotomayor noted,

[Today] [w]e are no longer so unaware. [emphasis added] Courts and corrections officials must accordingly remain alert to the clear constitutional problems raised by keeping prisoners like Apodaca, Vigil, and Lowe in “near-total isolation” from the living world… in what comes perilously close to a penal tomb.

These recent opinions show a clear desire to change how the Eighth Amendment's conditions standard is interpreted. This urge comes from a clear admission of the inhumanity inherent in keeping a person in extreme isolation for an excessively long time. However commendable, such recognition still overlooks the actual constitutional "crux" of solitary confinement: extreme isolation itself. The following sections specifically address this issue.

THE BRAIN IN SOLITUDE

The analysis of legal rulings regarding solitary confinement suggests that normal confinement and solitary confinement are largely considered equivalent. This equivalence stems from the fact that either type of confinement can be challenged under the Eighth Amendment only when specific accompanying material conditions of either type fail to meet constitutional standards. Thus, the defining element of solitary confinement—extreme isolation or social and environmental deprivation—is not, by itself, enough to qualify as an Eighth Amendment violation. In other words, social and environmental deprivation itself is not cruel and unusual punishment; as such, it is entirely constitutional.

Recently, a new approach has been taken to challenge solitary confinement under the Eighth Amendment. This approach draws on insights from social neuroscience regarding brain plasticity, social interaction, and environmental stimulation, as well as the effects of social and environmental deprivation on brain function and health. These findings have already been presented in courtrooms in several lawsuits to provide a comprehensive analysis of the impact of solitary confinement, offering additional "foundational evidence" of the harms of extreme isolation. The overall message from social neuroscience is that the psychological deterioration following social and environmental deprivation is linked to changes that occur in the brain. These brain changes "have implications beyond the immediately visible behaviors" and can lead to a wide range of negative psychological effects, many of which may be long-lasting or even permanent.

Although neuroscientific evidence has been used on a few occasions, it may offer new support for challenging solitary confinement under current constitutional standards. In the following discussion, this claim is explored in more depth. This involves a concise review of relevant scientific insights and data—much of which has also been introduced in court cases—to highlight three main neuroscience-based challenges to solitary confinement: first, that social interaction is as much a basic physical human need as food or water; second, that social and environmental deprivation causes traumatic brain changes that underlie potentially permanent psychological consequences; third, that the social pain induced by isolation has a physical basis in the brain, meaning it is fundamentally physical.

NECESSITY OF SOCIAL INTERACTION AND ENVIRONMENTAL STIMULATION FOR PHYSIOLOGICAL BRAIN FUNCTION

In his work "Politics," Aristotle famously wrote that "Man is by nature a political animal" and "a social instinct is implanted in all men by nature." Therefore, "men, even when they do not require one another’s help, desire to live together." More than two thousand years later, behavioral and neuroscientific fields have provided compelling and consistent scientific data confirming that human beings are wired by evolution to be connected. There is now a general agreement among psychological, anthropological, sociological, and neuroscientific disciplines that social connection, interaction, and belonging are innate and universal survival needs for humans, just as essential as food or water.

In their influential and widely cited work, Baumeister and Leary suggested that people are programmed to form and maintain interpersonal bonds because they are driven by their innate need to belong. This "need to belong" is an innate and universal motivation for human behavior. The authors defined this need as the drive to form and maintain strong, stable interpersonal relationships. They critically argued that this need is satisfied by frequent human contact and genuine bonds of care between individuals.

Baumeister and Leary proposed nine criteria to evaluate whether a given human need is a fundamental motivation for human behavior. Specifically, the relevant need should:

(a) produce effects easily under most conditions, (b) have emotional consequences, (c) guide how we process information, (d) lead to negative effects (like on health or adjustment) when unfulfilled, (e) motivate goal-oriented behavior to satisfy it (subject to patterns like substituting objects and reaching satisfaction), (f) apply universally to all people, (g) not be derived from other motivations, (h) influence a wide range of behaviors, and (i) have implications beyond immediate psychological functioning.

The authors then reviewed extensive evidence showing that belonging and social connection meet all of these criteria. Based on this, they concluded that the need to belong is indeed a fundamental human need.

Different scientific research perspectives support Baumeister and Leary’s conclusion. For example, several studies have suggested that social interaction influences the development and expression of executive functions (higher-level cognitive skills). Additionally, social engagement and participation in meaningful social activities have reportedly helped people maintain their thinking skills better and delay cognitive decline in middle and older adulthood. Epidemiological studies have linked social connection and meaningful interactions with better physical and mental health, as well as lower rates of illness and death. Other studies have also indicated that consistent meaningful social connections and bonds help individuals develop and maintain socio-emotional skills, such as empathy and emotion regulation, which are important factors for positive social attitudes and behavior. Importantly, these insights align with findings from studies on crime desistance (stopping criminal behavior).

Brain function helps explain why social connection and interaction are vital for human beings. Following Dunbar’s "social brain hypothesis," Matthew Lieberman has proposed that the brain size of different species—specifically, the size of their neocortex—corresponds to the size of their respective social environments. According to this hypothesis, humans have large brains—and the largest neocortex among all species—to meet their complex needs for socialization. Specifically, the human brain is organized to perform social thinking to navigate complex social interactions and environmental surroundings.

In the same vein, Daniel Siegel has suggested that the brain is "a social organ." On one hand, the brain triggers our thought processes and bodily experiences when exposed to social stimuli, thereby guiding our behavioral responses toward others and contributing to our social skills and relationships. Essentially, the brain is the organ that enables social interactions, as it maintains our connections with other individuals. On the other hand, physiological and neurological reactions are directly and profoundly shaped by social interactions. These interactions, which range from face-to-face conversations to feeling another person's touch, act as modulators, similar to interpersonal "thermostats" that constantly shape our brain function.

Consistent with these insights, key research on brain plasticity has shown that positive social engagement leads to positive changes in the neural circuits that support cognitive functions, socio-affective skills (e.g., empathy), and social behavior throughout a person's life. These changes have been linked to higher cognitive performance, psychological well-being, and prosocial behavior.

Studies on social interaction and brain plasticity relate to those on the continuous influence of environmental stimulation on the brain. These studies have mostly used animal models. For example, studies with rodents have shown that rodents raised in "enriched environments" and surrounded by their peers exhibited normal developmental pathways in the structure and function of several brain areas. These areas support various functions, from typically cognitive ones to emotion-related functions like learning, memory, and emotion regulation. Importantly, these animal groups also showed normal social tendencies.

Several studies have suggested that some of these physical and functional characteristics can be explained by neurogenesis, which is the growth of new cells in brain regions. Evidence implies that enriched environments "enhance cell proliferation and neurogenesis in the brain, notably in the regions critical for social interaction, memory, and communication," including the hippocampus. As discussed shortly, social and environmental deprivation appears to hinder neurogenesis in these same brain regions and cause negative psychological and behavioral consequences.

In summary, there is an inseparable, two-way relationship between the brain and the social environment. On one hand, the complex organization of the human brain allows humans to fulfill their biological need to connect and interact with their social world. On the other hand, the social world enables, nourishes, and shapes the brain mechanisms that support the cognitive, emotional, and socially relevant abilities that allow humans to function individually and socially. Thus, social connection or interaction in stimulating environments is crucial for protecting brain function and health. According to Lieberman, "[n]o one will die from lack of social contact over a few days, but people will show evidence of being in a deprived state within a short period and a lack of social connection will likely produce a wide array of negative outcomes for an individual’s mental and physical well-being before long." Therefore, when social and environmental connection is absent, the brain—and consequently the person—will likely suffer profound traumatic consequences in the long term.

THE NEUROBIOLOGICAL EFFECTS OF SOCIAL AND ENVIRONMENTAL DEPRIVATION

A large amount of clinical and experimental research has documented the effects of solitary confinement on both healthy and unhealthy incarcerated populations. This research consistently points to the same dramatic conclusion: solitary confinement can cause potentially permanent cognitive, emotional, and physiological damage.

For instance, in his clinical observational studies, Stuart Grassian reported three main "typical features" of the general psychological effects of solitary confinement: (1) perceptual distortions, illusions, and hallucinations in various senses; (2) emotional disturbances including anxiety and panic attacks; and (3) obsessive, intrusive thoughts sometimes accompanied by compulsive behavior. According to Grassian, the most affected individuals may even develop psychotic disturbances with a dissociative character, while those less affected still experience significant psychiatric harm, including intense anxiety, obsessive thinking, agitation, paranoia, and irritability.

Grassian’s findings support those from other psychological studies that have linked life in solitary confinement to a wide range of negative psychological effects, including rage, irrational anger, fears of persecution, lack of impulse control, severe and chronic depression, appetite loss, heart palpitations, withdrawal, and apathy, among others. This body of literature has also documented the dehumanizing effects of social isolation, which include, but are not limited to, a lack or loss of belonging, self-esteem, meaning, and self-identity. The dehumanizing effects of social isolation have been linked to a higher risk of engaging in harmful, antisocial, and destructive behavior.

Notably, research suggests that the psychological impairments caused by solitary confinement continue even after an individual is released from prison and returns to a social environment. Specifically, people released back into the community after serving time in solitary confinement are "incapable of accommodating to life." This is due to an over-sensitivity to sensory stimuli, leading to intolerance of typical daily noises, like the chaos of a restaurant, and social stimuli, including an inability to participate in family moments, such as eating meals together.

Scientific research has begun to identify the brain changes that appear to be linked to the psychological effects of social and environmental deprivation (or extreme isolation). For example, electroencephalography (EEG) studies have shown that a few days in solitary confinement can cause brain injury-like wave alterations. These alterations have been linked to an over-sensitivity to external stimuli, inadequate attention and alertness to the environment, as well as "a complete breakdown or disintegration of the identity of the isolated individual."

Clinical and experimental studies that have documented the effects of solitary confinement on the brain are supported by a strong body of experimental animal research. This research helps explain the various brain mechanisms that underlie the psychological and psychiatric symptoms observed in incarcerated individuals who have been isolated for long periods. These studies have collectively revealed that social and environmental deprivation negatively impacts both brain structure and function, including reduced cortical volume, fewer neuronal connections in cortical areas and the hippocampus, decreased myelin production, and altered activity in the reward system and the amygdala. These brain changes have been connected to detachment from the environment, hostility toward others, high levels of aggression, as well as an increased risk of developing several behavioral conditions that mimic psychiatric diseases and disorders in humans, including neurodegenerative disorders and schizophrenia. Importantly, physical and functional changes in the brain can occur even after a short period and appear to continue after the subject is reintroduced to a social environment.

A significant body of research has examined the neurobiological effects of chronic stress caused by social and environmental deprivation. For instance, studies with rodents have shown that rodents housed alone, unlike those in enriched environments, develop a smaller cerebral cortex and shorter connections between neurons in brain areas involved in spatial information processing, memory, social information, and emotion regulation, including the hippocampus. Additionally, some studies have linked physical and functional reductions in the hippocampus to decreased neurogenesis (the growth of new brain cells) in that area. These damages have been connected to long-term mental health conditions in humans, such as memory loss, cognitive decline, depression, and post-traumatic stress disorder.

Beyond the hippocampus, another limbic region that appears to be affected by social and environmental deprivation is the amygdala, which manages emotional responses to perceived stimuli. The amygdala is also involved in experiencing and processing fear and anxiety. Studies with rodents have indicated that high stress increases cortisol levels, which in turn alter neuron growth in the amygdala and produce negative psychological and behavioral effects like anxiety, deficits in social interaction, and poor regulation of social behavior.

At the cortical level, studies with isolated rodents in poor environments observed reduced levels of myelination (the protective covering of nerve fibers) in the prefrontal cortex. Impaired myelination in this brain area has been reported in a number of psychiatric illnesses, including anxiety, autism, schizophrenia, and depression. Other studies with rats have shown that rats raised in isolation exhibited reduced medial prefrontal cortex (mPFC) volume compared with rats raised in groups. Among humans, reduced mPFC volume has been linked to several core symptoms of schizophrenia, such as neophobia (fear of new things), impaired memory, and sensorimotor gating (filtering out unnecessary sensory information).

Studies on social isolation correlate with and complement research on loneliness, which is the subjective feeling of being isolated. Although loneliness is not always directly linked to physical and objective isolation, such isolation can contribute to feelings of loneliness. Behavioral research on loneliness has identified perceived social isolation as a risk factor for "poorer overall cognitive performance, faster cognitive decline, poorer executive functioning, more negativity and depressive cognition, heightened sensitivity to social threats" as well as "an increased implicit vigilance for social threats along with increased anxiety, hostility, and social withdrawal;… decreased impulse control in favor of responses highest in the response hierarchy (i.e. prepotent responding); increased negativity and depressive symptomatology…." Furthermore, several studies have highlighted connections between the symptoms of loneliness and the neurobiological changes seen after objective social isolation.

Taken together, there is strong evidence of the damaging and long-lasting neurobiological effects of social isolation and environmental deprivation. This evidence suggests that many of these effects are difficult to reverse, even after an individual is reintroduced into a social environment. It is acknowledged that many questions about the exact implications of social and environmental deprivation for the human brain and behavior remain unanswered. These include how long a person can be isolated without risking irreversible damage, or how factors such as age, gender, or personal background affect the severity of social and environmental isolation for the brain and behavior. As observed, many of these questions are difficult to study in human subjects.

While answering these questions is crucial for fully understanding the exact effects of solitary confinement on the brain and behavior, current evidence is reliable and consistent enough to suggest that "increased social isolation and diminished physical contact contribute to and reinforce problematic neurobiological patterns." Therefore, the depriving conditions of solitary confinement will most likely "generate or exacerbate neurobiological deficits and maladaptive behaviors... [t]his becomes a significant issue, especially for individuals who are chronic offenders, where existing neurobiological vulnerabilities are intensified in settings of confinement and segregation, thereby reinforcing maladaptive patterns of behavior." Overall, neuroscience research indicates that the essential features of solitary confinement, namely social and environmental deprivation, can alone cause significant brain damage, all of which risks leading to long-lasting or even permanent traumatic psychological and physiological consequences. So far, these consequences have been largely overlooked in courtrooms.

SOCIAL PAIN IS PHYSICAL

A key insight from social neuroscience regarding the impact of social and environmental deprivation on the brain concerns social pain. As noted, common understandings of pain and the law itself are based on the assumption that physical pain and social (mental) pain differ in their characteristics and nature. Physical pain is generally understood as pain from a bodily injury or the deprivation of a physical need; as such, it is objective, measurable, and tangible. Meanwhile, social pain is viewed as purely mental, subjective, and almost "non-existent." Therefore, it is largely overlooked as an inner experience of the individual with no tangible effects. As noted, this distinction between types of pain is widespread in law and also appears in legal rulings on prison conditions regarding solitary confinement. To challenge these common assumptions, a growing body of research in social neuroscience has suggested that social pain is deeply rooted in the brain, meaning social pain is fundamentally physical.

The most influential theory of negative social experience, called the shared representation theory, suggests that physical pain and social pain "rely on shared neural circuitry." According to this idea, the experience of social pain comes from the natural and universal human need for social connection and belonging. From an evolutionary perspective, this natural need likely originates from the long period during which mammalian infants critically depend on maternal attachment, care, and nurturing to survive. The lack of these fundamental needs creates a feeling of rejection, which the individual perceives as painful and distressing. Based on this survival need, it is possible that "the social attachment system—which ensures social connection—may have piggybacked directly onto the physical pain system, borrowing the pain signal itself to indicate when social relationships are threatened." Thus, the experience of social pain may be seen as an adaptive way to prevent and survive the threat of social rejection and exclusion. As Lieberman and Eisenberger put it, "[j]ust as evolution has wired us to feel pain when we lack food (e.g., hunger), water (e.g., thirst), or shelter (e.g., freezing, sunburn), perhaps evolution has wired us to feel pain when we lack... social connection."

Building on this perspective, neuroimaging research conducted by Lieberman and Eisenberger has reported a significant overlap between physical pain and social pain in the brain. Specifically, their studies have indicated that the experience of physical pain involves two separate components: a sensory component, supported by the primary and secondary somatosensory cortex and the posterior insula; and an affective component, which is the distressing experience of pain, supported by the dorsal anterior cingulate cortex (dACC) and the anterior insula (AI). Neuroimaging studies from this line of research have suggested that the experience of social pain activates neural pathways typically involved in the affective component of physical pain processing—namely the dACC and the AI. These studies have also shown that people who are more sensitive to physical pain will also be more vulnerable to experiencing social pain. Interventions aimed at relieving physical pain also appear to be effective in relieving social pain.

Social pain has been linked to both physical and objective isolation (meaning an actual lack of social connection) as well as perceived isolation (loneliness). Several laboratory studies within the reported line of research have explored the link between the experience of social pain and social disconnection (caused by social isolation) through neural activity in the brain regions that support this form of pain. These findings can likely explain why individuals with higher levels of objective or subjective isolation are at a greater risk of developing physical and mental health problems and even a higher risk of mortality. As Eisenberger has explained, "given that the dACC and AI are involved in responding to social disconnection, these regions may have a role in translating experiences of social disconnection into downstream physiological responses—such as heightened inflammatory activity, the immune system’s first line of defense against foreign agents and infection...." Increased inflammatory activity has been found to relate to negative physical and mental health outcomes, including heart diseases and depression.

Finally, this line of functional magnetic resonance (fMRI) studies has also begun to investigate how social pain affects aggression through activation in the dACC and the AI. Preliminary results show a positive connection between increased activity in these two brain regions (linked to the experience of social pain) and increased levels of aggression in socially rejected individuals who have less executive functioning (regulatory capability). These results suggest that social pain contributes to aggressive reactions among socially rejected individuals.

In partial contrast with Eisenberger’s and Lieberman’s work, another fMRI study, led by Tor Wager, used a more detailed analysis and identified distinct neural representations of physical pain and social pain within core pain-processing brain regions and across other brain areas. Notably, this work indicates that physical pain and social pain involve independent neural representations despite common fMRI activity at a broader anatomical level (e.g., in the dACC and AI). Thus, rather than recruiting physical pain circuitry, social pain appears to involve different emotional representations in the brain. Based on these findings, these researchers have proposed that physical pain and social pain are ultimately distinct types of emotional experiences that may lead to unique psychological consequences; therefore, they require different types of interventions. Still, the authors have highlighted that physical pain and social pain may still be functionally related and influence each other. For instance, evidence indicates that individuals who suffered emotional trauma are at a higher risk of developing pain disorders.

Despite the scientific disagreement over whether social pain is neurologically similar to physical pain, neuroscientific findings on the nature of social pain collectively offer two critical insights for this article. First, the lack of social connection—meaning social isolation—leads to a range of negative emotional states, adverse psychological effects, and harmful behavioral patterns linked to the pain of being socially excluded or rejected. Second, this social pain has a physical reality in the brain. As such, it should be considered "real pain," rather than a "metaphorical pain." Importantly, the experience of social pain is not less serious or less harmful than that of physical pain. Rather, its consequences for an individual may well be more distressing and damaging than those following forms of physical pain. Thus, continuing the hierarchy of physical versus social pain by favoring the former over the latter is problematic. Most importantly, it severely overlooks the kind of suffering that social pain due to isolation can cause, which can be equally intense and equally (or even more) traumatic and long-lasting compared with the physical pain one might experience from lacking a tangible, physical need.

SOLITARY CONFINEMENT IS PER SE CRUEL AND UNUSUAL PUNISHMENT

The body of neuroscientific research on the vital importance of social interaction for brain structure and function, combined with insights into the damaging effects of social isolation and environmental deprivation on the brain, mind, and behavior, could revitalize challenges to solitary confinement.

While more precise scientific answers are needed to fully understand the variety and extent of solitary confinement's implications for the brain and behavior, existing evidence can provide additional empirical support to challenge the core of solitary confinement: extreme isolation. As noted, insights from neurosciences regarding the traumatic consequences of extreme isolation align with those from various international bodies who have emphasized that "all forms of solitary confinement without appropriate mental or physical stimulation are likely, in the long term, to have damaging effects."

Based on these insights, the remainder of this article presents three main points supporting the argument that solitary confinement, as it is currently administered in many jurisdictions, inherently violates the Eighth Amendment's ban on cruel and unusual punishments. First, the core feature of solitary confinement—extreme isolation or social and environmental deprivation—fails to meet the current conditions standard. Second, there is a clear imbalance between the widespread traumatic and potentially permanent implications of social and environmental deprivation and the prison's legitimate goals that solitary confinement is intended to serve. Furthermore, and more broadly, solitary confinement contradicts all justifications for punishment. Acknowledging that solitary confinement fails to meet any relevant Eighth Amendment requirement implies that solitary confinement is inherently unconstitutional.

FAILURE TO MEET CURRENT CONDITIONS STANDARD

The body of neuroscientific research on the effects of social and environmental deprivation on the brain provides a strong scientific basis for the argument that social and environmental deprivation (or extreme isolation)—the core of solitary confinement—qualifies as an Eighth Amendment violation under all parts of the current conditions standard. This section discusses each part in turn.

Social interaction and environmental stimulation as basic human needs

Consistent with evolutionary perspectives, neuroscientific research has provided a compelling argument for classifying social interaction as a basic human survival need, on par with other identifiable physical needs such as water, food, or shelter. As discussed, social interaction is simply inherent to human nature, as humans are fundamentally social beings. This inherent quality stems from the mutual and inseparable relationship between the brain and the social environment. Furthermore, the neurobiological need for social interaction includes and is complemented by the need for environmental stimulation. As discussed, environmental stimulation significantly contributes to brain development and behavior, and the human brain must constantly receive a variety of sensory inputs from the external environment to function properly. Overall, the evidence discussed above indicates that social interaction and environmental stimulation are essential conditions for healthy brain function. As such, depriving human beings of social contact and environmental stimulation is equivalent to depriving them of their very nature.

Acknowledging the vital importance of social interaction in stimulating environments implies that forcing individuals into isolation in tiny, environmentally poor cells is enough, by itself, to deprive them of basic human needs. Accordingly, specific material conditions of solitary confinement (e.g., lack of heating, proper bedding, or winter clothing) should be seen as circumstances that worsen and are therefore secondary to an underlying condition—extreme isolation—that is alone sufficient to constitute a serious deprivation of basic human needs.

Importantly, including social interaction and environmental stimulation in the range of basic human needs also challenges the courts' assumption of equivalence between normal confinement and solitary confinement. As reported, courts have supported the view that solitary confinement is legitimate as long as its conditions, such as the provision of nutrition and shelter, are not significantly different from those affecting the general prison population. Thus, solitary confinement is not cruel and unusual as long as it guarantees the same basic human needs that are ensured to the general prison population. However, such equivalence fails to consider that extreme isolation is the condition that makes the two types of confinement fundamentally different. This difference arises precisely from the fact that solitary confinement deprives individuals of a survival need that normal confinement guarantees. Considering this fundamental distinguishing aspect and its consequences, normal and solitary confinement cannot be placed on the same level. Rather, the evaluation of solitary confinement should be based on its own criteria, which should systematically recognize social interaction as a fundamental need rather than merely a privilege.

Socio-environmental deprivation (extreme isolation) entails an objectively serious risk of physical harm

If the vital role of social interaction and environmental stimulation for human brain and behavior is not sufficient to establish them as basic physical needs, evidence of the risks that social and environmental deprivation poses to the brain adds significant weight and encourages a reconsideration of the "substantial risk of serious harm" requirement in relation to solitary confinement.

As discussed, the brain changes or deteriorations that follow social and environmental deprivation appear to underlie a number of negative cognitive, emotional, and behavioral patterns, and they have also been reported in major psychiatric disorders, including depression and schizophrenia. These findings support and corroborate the existing strong body of psychological studies that have documented the dramatic psychological and psychiatric effects of solitary confinement. Moreover, the brain and psychological damages due to social and environmental deprivation have been found to contribute to physical health problems and even increase the risk of mortality. From this perspective, the damaging effects that solitary confinement could impose on prisoners can be long-lasting or even permanent.

Equally important are insights into the nature and implications of the social pain caused by social isolation. Besides indicating that social pain has physical reality, neuroscientific research has crucially suggested that the experience of social pain can be far worse than that of physical pain in many respects. Social pain has been linked to a series of psychological symptoms, including humiliation, low self-esteem, harmful behavioral tendencies (including aggression), and lower levels of physical and mental health, especially in the long term. Thus, even if the traumatic effects of social pain are not immediately visible, they may appear and worsen over time.

By translating neuroscientific insights into the language of prison conditions law, one can make the following observations. First, social and environmental deprivation does involve an objectively serious risk of physical harm that is comparable to that of food or sleep deprivation. Even if the harm that solitary confinement imposes on the brain translates into mental deterioration, and is therefore mental, it is also undeniable that "the type of severe psychological deterioration observed in solitary confinement is due to physical harms imposed on the brain." As such, it is ultimately physical.

Second, the harm that solitary confinement imposes on the brain underlies a number of long-lasting or potentially permanent mental, physical, and physiological conditions. Therefore, the possible harms of solitary confinement are not only damaging but also potentially permanent. Lastly, and perhaps most importantly, the risk of such physical harms may appear even after a short period of extreme isolation. As mentioned, (neuro)science has not yet precisely determined how long an individual can spend in isolation without suffering irreversible brain damage. However, there is a consensus across scientific disciplines (including neuroscience) that the amount of time an individual spends in socially and environmentally deprived conditions positively correlates with the degree of risk that they will deteriorate neurologically, physiologically, psychologically, and physically.

It is acknowledged that not all individuals will necessarily and inevitably suffer irreversible damages, and not everyone will experience the same kinds of traumas after the same amount of time. However, as Bennion correctly noted, "[t]he fact that serious risks may never materialize in serious harm (or that harm may not be imminent) is not decisive for... the test." Furthermore, the risk of undergoing serious brain and mental deterioration following solitary confinement is universal: any person is vulnerable to such risk, regardless of their history of mental illness.

In light of the above insights, solitary confinement alone also meets the "substantial risk of serious (physical) harm" requirement of the objective prong of the conditions standard. By depriving individuals of a minimal life necessity, solitary confinement inherently risks inflicting unnecessary suffering characterized by damaging and potentially permanent consequences. As the Court has repeatedly stated, the interpretation of the Eighth Amendment changes along with the knowledge and standards of decency of an evolving society. A punishment that risks inflicting damaging and potentially permanent harm upon individuals exceeds contemporary standards of decency, and no civilized society should tolerate such a toll on human beings.

Deliberate indifference follows from extreme isolation

As noted earlier, the subjective aspect of the conditions standard has been criticized by scholars, especially in solitary confinement cases. It can be extremely difficult to prove that prison personnel or administrators were deliberately indifferent to the harms inflicted upon prisoners by a serious deprivation of basic human needs. Such challenging proof can hinder the success of legitimate Eighth Amendment claims based on harmful solitary confinement conditions.

Courts have acknowledged that when the risk of serious harm from a confinement condition is objective and generally known, such objective proof is also sufficient to infer the blameworthy state of mind of prison personnel. Regarding solitary confinement, several court opinions have questioned the need for explicit proof of deliberate indifference, given that placing prisoners in solitary confinement poses a substantial risk of serious harm. For instance, the court in Wilkerson observed that "basic common sense indicates that ‘lack of exercise, social isolation, and/or stress are associated with [deleterious] conditions’... [Therefore, a] court ‘may infer the existence of this subjective state of mind [i.e., deliberate indifference] from the fact that the risk of harm is obvious.’" Likewise, opinions in Supreme Court cases have highlighted the growing awareness of the damages of solitary confinement in modern American penal systems. Such damages have been extensively documented and recognized by scientific, legal, and international sources.

Furthermore, several authors have supported presuming guilt for prison officials in cases seeking injunctions (court orders to stop an action). For instance, it has been suggested that "prisoners could certainly show by the time of trial that authorities were aware of either the actual harm or risk of harm caused by solitary confinement." Thus, when harmful conditions are allowed to continue, courts may infer the culpable mindset of prison officials from the conditions themselves without also requiring explicit proof of their mindset.

This article's thesis further supports and strengthens these claims. When acknowledging that the core condition of solitary confinement, namely extreme isolation, itself amounts to a cruel and unnecessary infliction of pain and constitutes cruel and unusual punishment, the subjective part of the test loses its purpose and becomes unnecessary. Given the growing general awareness of the objective harms linked with solitary confinement, proof of social and environmental deprivation is sufficient to infer that prison officials acted with deliberate indifference. This is because extremely isolating a prisoner is essentially depriving them of a basic human need and carries an objectively serious and well-known risk of harm. Therefore, a fact-finder could conclude that by keeping a prisoner in solitary confinement despite the obvious health risks, both physical and psychological, the prison staff acted with deliberate indifference to the substantial risk of consequent harm.

FAILURE TO MEET THE INTENDED PENOLOGICAL AIMS

The evidence presented above regarding the widespread consequences of solitary confinement also challenges the supposed balance between the "pains" of solitary confinement and the legitimate prison interests of discipline, security, and safety. This "newly" emerging imbalance arises from the fact that social and environmental deprivation, especially when prolonged, risks causing severe brain deterioration, even in individuals without a history of mental illness. Such deterioration may not be limited to the period of isolation; rather, given the long-lasting psychological consequences they entail, the effects of such deterioration risk continuing even after an individual is reintroduced into a social environment, whether it be the prison or the general community. The risk of suffering brain damage due to extreme isolation is an excessive—and therefore, extremely unbalanced—cost for any alleged legitimate prison interest to justify.

These claims reinforce the strong body of evidence showing that neither short-term nor long-term stays in solitary confinement achieve specific deterrent effects by reducing subsequent disciplinary infractions or prison incidents. Instead, evidence shows that stays in solitary confinement appear to produce the opposite effect. Moreover, jurisdictions that have restricted the use of solitary confinement have seen a decrease in prison violence. Thus, limiting the use of solitary confinement does not undermine the ability of prison administrators to control the prison population or maintain safety; it may actually increase it.

Acknowledging these claims may prompt courts to reconsider their (often excessive) deference to prison administrations regarding the management and application of solitary confinement practices. Specifically, it could prompt courts to carefully scrutinize the "legitimate penological justifications" that prison administrations cite to defend their use of solitary confinement. This could fully realize the constitutional protection of people in custody that is at the core of the Eighth Amendment.

From a broader perspective, evaluating the legitimate prison justifications for a given prison condition or correctional practice under the Eighth Amendment must consider the advancement of knowledge as it reflects the evolution of society and its standards of decency. Currently, there is a general consensus among domestic and international bodies that disfavors solitary confinement, suggesting that standards of decency have moved away from using solitary confinement to serve its intended prison purposes. Increased knowledge also shows (the reasons for) the greater effectiveness of less restrictive and less painful methods to achieve the same prison goals. Thus, no prison interest can justify the systematic and indiscriminate use of solitary confinement. Moreover, no prison interest can outweigh the damages that solitary confinement risks imposing on incarcerated individuals. It is acknowledged that solitary confinement may still be justified in instances requiring an individual’s temporary protection or for the most serious, violent offenses or infractions, but only when other measures have been tried without satisfactory results. Even in such cases, separating an individual from the rest of the prison community can still be handled in a more humane and less restrictive way.

THE ANTITHESIS BETWEEN SOLITARY CONFINEMENT AND THE GOALS OF PUNISHMENT

Solitary confinement and its effects are also inconsistent with the goals of punishment: retribution, incapacitation, deterrence, and rehabilitation. As such, it lacks any purpose within the penal system. Although this broader perspective on punishment is uncommon in Eighth Amendment analyses of (solitary) confinement cases, explaining why solitary confinement goes against each main justification for punishment can still offer scholarly value.

Starting with retribution, analyses based on this concept generally include two parts. The first, which is objective, evaluates a punishment based on the seriousness of the crime committed. The second, which is subjective, evaluates a punishment based on the degree of the perpetrator's blameworthiness. Blameworthiness evaluations also include the individual characteristics of a perpetrator, such as their age or mental capabilities. Therefore, from a retributive perspective, a punishment is disproportionate when it is excessively severe relative to the crime and the perpetrator's overall degree of blameworthiness and, thus, culpability.

For the purposes of this article, solitary confinement is assessed against another critical aspect of retributive theory: the preservation and respect for the moral rationality of perpetrators. The idea of moral rationality is undeniably central to any retributive punishment. Retribution assumes that the perpetrator is a rational moral agent capable of understanding the meaning and consequences of their actions and freely chooses to act unlawfully. Based on this assumption, retributive punishment aims to ensure that perpetrators "are capable of understanding the wrongs they have committed and the fairness of the penal sanctions imposed on them by the state in response to those wrong." Accordingly, retributivism insists on structuring legal punishment so that it is, at minimum, consistent with treating offenders as rational moral beings.

Retributivism requires that imprisonment deprives perpetrators of their freedoms by significantly reducing their privileges to live autonomous lives. However, retribution does not require that imprisonment also destroys the abilities that constitute moral personhood, such as "physical and psychological health, work and interaction with others." From a retributive perspective, these abilities and inclinations need to be regularly exercised to preserve prisoners' capacity "to comprehend and respond constructively to the reasons for which they are being punished."

From this reasoning, solitary confinement does not align with this fundamental aspect of retributive punishment. Solitary confinement risks inflicting traumatic brain and mental damage on prisoners, all of which compromise the cognitive and emotional abilities that support practical reasoning skills, and "cause further atrophy of what may have already been weak capacities to identify with and feel for others." Furthermore, the long-lasting or even permanent physiological, mental, and physical damage that solitary confinement may cause can continue even after a prisoner has served their sentence. Therefore, solitary confinement, which can inflict long-lasting or even permanent losses on perpetrators, makes a prison sentence disproportionate to the seriousness of the crimes committed. Such an outcome is simply contrary to any mainstream retributive perspective.

Solitary confinement also fails to meet the consequentialist goals of punishment, namely incapacitation, deterrence, and rehabilitation. Incapacitation refers to how punishment, especially imprisonment, prevents perpetrators from committing further offenses by physically removing them from society. Solitary confinement, particularly in supermax facilities, serves this purpose during the period of confinement. However, the benefit of this incapacitation argument for public safety requires further analysis of the specific deterrent effects of solitary confinement.

Theories regarding the use of solitary confinement emphasize its potential to deter future crime. However, scientific evidence disproves the effectiveness of solitary confinement as a tool to deter repeat offenses or change prisoners' behavior. There is evidence that prisoners in solitary confinement in supermax prisons fare even worse than prisoners in the general population once they are released. For instance, an epidemiological study by Maers and Bales compared the rates of repeat offenses among individuals who had been in solitary confinement with those who had been normally confined. They found that solitary confinement was associated with a higher risk that formerly incarcerated individuals would commit a violent crime after being released. Other epidemiological studies have replicated this finding. The reasons for the increased risk of repeat offenses largely stem from the brain alterations due to solitary confinement, which have been linked to negative psychological symptoms and mental health issues known to be risk factors for socially dysfunctional behaviors, including antisocial conduct.

Finally, solitary confinement does not serve the rehabilitative ideal of punishment. Social rehabilitation clearly aims to reintegrate convicted persons into society upon their release so they can lead a law-abiding and self-supporting life. Thus, it seeks to reestablish positive relationships between perpetrators and the rest of society by facilitating self-reform and change based on relational processes. Rehabilitation critically promotes as much inclusiveness and positive social engagement as possible while perpetrators serve their sentence, as this can facilitate their social reintegration into the community.

In addition to opposing the core values and aims of rehabilitation theory, the potential harms of solitary confinement, including a greater tendency toward aggression and other harmful psychological and behavioral patterns, can seriously compromise an individual's social functioning. Therefore, these harms severely hinder the rehabilitation and resocialization process, making it more difficult, if not nearly impossible in some cases.

To conclude, the type and extent of harm that solitary confinement can inflict on individuals do not align with and are therefore disproportionate to any prison justification. In view of this, solitary confinement constitutes an unnecessary and wanton infliction of pain because it not only deprives individuals of their basic social and environmental biological needs but also lacks any kind of penal justification. The suffering that solitary confinement imposes is unnecessary and violates every relevant perspective under the Eighth Amendment. No prison interest or aim can justify its infliction; solitary confinement is inherently cruel and unusual punishment.

A PATH FORWARD: ABOLISHING SOLITUDE IN PRISON

The arguments presented in this article ultimately support the conclusion that solitary confinement, as it is still practiced in many facilities or penal systems, should be eliminated entirely. This conclusion aligns with the many domestic and international organizations, movements, and associations that have called for abolishing solitary confinement or at least limiting its use to exceptional and strictly regulated circumstances.

Separating a prisoner from the rest of the prison population should always be a last resort intervention to manage extreme situations—which must be properly documented by prison staff and possibly overseen by specialized committees—only when absolutely necessary to achieve legitimate prison goals. In such cases, the separation of an individual from the rest of the prison community should be subject to strict temporal, social, and environmental standards. These (possibly uniform) standards are needed to counter most arbitrarily used forms of solitary confinement, as well as a constitutional weakness that allows prison administrations to use solitary confinement with little judicial oversight.

Regarding time limits, the ASCA-Liman survey reported time intervals ranging from between 1 and 15 days to more than six years across different jurisdictions. Although fewer people were kept in solitary for 1-15 days, higher percentages were reported for periods in solitary of at least one month to over six years.

More empirical research is needed to determine the exact maximum time limit for depriving an individual of constant social contact without causing irreversible damage. Nevertheless, acknowledging that such deprivation risks causing or worsening physical, physiological, and psychological negative effects even after just a few days provides sufficient grounds for adopting uniform maximum time limits that align with existing empirical knowledge and domestic and international guidelines. Given the current lack of legal precedent on duration limits for solitary confinement, the strength of international and domestic guidelines recommending a maximum of 15 days of solitary confinement should be used as a benchmark to set uniform time standards in all jurisdictions. All states should adhere to these standards, with any violation constituting an Eighth Amendment violation.

In addition to setting uniform time limits for solitary confinement, uniform social interaction standards are also needed. The ASCA-Liman survey also reported positive data from several jurisdictions that have implemented specific policies in recent years to restrict the use of solitary confinement to the most objectively serious cases. These policies aim to improve the "social" conditions for people housed in solitary cells. Several jurisdictions have implemented policies that allow more time out of the cell, outdoor recreation activities, classes, job training, rehabilitation, and re-entry programs for restricted individuals. However, only a few of them have increased visiting hours. Some policies even offer training for correctional officers to learn alternative responses to prison violence that focus on dialogue, accountability, and cooperation. Notably, statistics show that both prison incidents and the overall rate of repeat offenses upon re-entry to the community have decreased. These scattered changes are encouraging and demonstrate a growing recognition that solitary confinement is counterproductive and can be extremely damaging. Ensuring that all correctional facilities adopt and apply social standards—including recreation, education, rehabilitation programs, and visiting hours with significant others—for prisoners temporarily separated from the rest of the community is crucial to counteract the negative effects of isolation and aid in their social rehabilitation and re-entry process.

Finally, while this suggestion applies to correctional facilities in general, the design of separation cells should follow strict environmental standards. On several occasions, the Court stressed that "the Constitution does not mandate comfortable prisons." However, it also stated that the Constitution "neither does... permit inhumane ones." The empirical studies reported above indicate that environmental surroundings—whether enriched or deprived—significantly influence brain structure and function, as well as psychological well-being and social behavior. Tiny and environmentally sparse cells risk exacerbating the negative effects of a lack of social interaction.

Several authors have called for making correctional facilities as humanized and home-like as possible. Positive international examples show that home-like cells with natural light, even in maximum security facilities, where prisoners are provided amenities such as proper bedding, furniture, or reading materials, contribute to prisoners' physical and psychosocial well-being. Such generalized well-being has been found to positively contribute to reduced institutional misconduct and overall repeat offenses.

It is admittedly difficult to expect such a dramatic change in U.S. facilities in the immediate future. Nevertheless, it is crucial to acknowledge that such realities exist and are effective. Most importantly, those realities convey an important lesson of "dignity and humanity that is the birthright of every person, and... respect [for] the collective dignity and humanity of society." These are the values and rights that inspire the Eighth Amendment and should, accordingly, inspire the abolition of solitary confinement.

CONCLUSION

In the opening paragraph of her dissenting opinion in Apodaca, Justice Sotomayor wrote, "A punishment need not leave physical scars to be cruel and unusual." However, social and environmental deprivation can apparently leave too many scars, which may be visible and tangible. Solitary confinement is a damaging and dehumanizing punishment, as it deprives people of their biological needs, drastically alters their physiology, and causes severe psychological and physical harm. It is increasingly an appropriate time to address the many, potentially incurable scars that solitary confinement may inflict on incarcerated individuals. Continuing to ignore these scars can only make them even more profound.

INTRODUCTION

The use of solitary confinement in the United States has gained significant attention. Official reports, legal and psychological studies, and media stories have highlighted numerous accounts of incarcerated individuals subjected to extreme isolation for varying periods, often with limited social contact beyond prison staff and in poor living conditions. While this practice is common in many correctional facilities, solitary confinement is generally considered a legitimate tool for maintaining discipline, security, and safety within prisons.

Currently, there are no consistent rules or administration of solitary confinement across states. Each state's prison system largely determines its own policies and practices. This lack of consistent oversight has often led to abuses, prompting national and international calls for either the complete abolition or significant reform of solitary confinement in the U.S. These efforts have resulted in some reforms in certain areas, as well as recommendations and guidelines from the Department of Justice and national organizations. These guidelines aim to limit solitary confinement by setting maximum timeframes for isolation or by prohibiting its use for vulnerable populations, such as individuals with mental disabilities and juveniles.

Despite these efforts, progress in restricting or improving solitary confinement practices has been slow and uneven. An official report from the American State Correctional Association and Liman Center (ASCA-Liman) indicates that while the number of people in isolation has decreased in some states, it has increased in others.

Beyond the lack of uniform standards, the constitutional standard for solitary confinement under the Eighth Amendment, which prohibits cruel and unusual punishment, has been applied narrowly. The Supreme Court has ruled that prison conditions, including solitary confinement, are cruel and unusual if they inflict "unnecessary and wanton pain" on incarcerated individuals. This occurs when conditions deprive individuals of "basic identifiable human needs" to an extent that they cause harm or create a "substantial risk of serious harm," and when prison staff act with "deliberate indifference." Although not explicitly stated, courts also consider a state's "legitimate penological interest" when evaluating the constitutionality of a prison condition.

Regarding solitary confinement, courts, with few exceptions, have consistently applied this standard narrowly. They have often dismissed the general mental suffering caused by social isolation in deprived cells. Consequently, the duration of solitary confinement has often not been considered a separate factor in constitutional evaluations. In doing so, courts have frequently overlooked the unique impact of extreme isolation, also known as social and environmental deprivation, which distinguishes solitary confinement from standard incarceration.

More recently, a new approach to challenge the constitutionality of solitary confinement has emerged, drawing on insights from social neuroscience. This field examines the traumatic and potentially permanent effects of social and environmental deprivation on the brain. Research in social neuroscience suggests that social interaction in stimulating environments is crucial for healthy brain function and mental well-being. Studies have shown various forms of brain damage can result from even brief periods of social and environmental deprivation. These damages have been linked to several potentially irreversible mental conditions. Additionally, many mental conditions associated with these brain changes due to isolation in deprived environments are linked to an increased risk of harmful actions and socially dysfunctional behaviors, including aggression. Another significant finding from this area of neuroscience is the physical nature of social pain experienced from isolation.

Neuroscientific findings on the harmful consequences of social and environmental deprivation support and strengthen previous research on the detrimental psychological effects of solitary confinement. These findings also offer new arguments for challenging solitary confinement. First, they support the claim that solitary confinement inherently deprives individuals of basic human needs, specifically social interaction and environmental stimulation. Second, within a few days of isolation in a deprived setting, there is a risk of physical brain damage. Third, the resulting mental health and behavioral problems could persist even after an individual returns to a social environment, potentially affecting long-term social functioning. Based on these insights, this article argues that solitary confinement is inherently cruel and unusual under all aspects of the current conditions of confinement standard. It also explores ways to significantly rethink solitary confinement practices.

The article is structured as follows: Part I analyzes conditions of confinement legal rulings to outline the current constitutional status of solitary confinement. Part II discusses how these rulings have largely ignored the general mental suffering caused by extreme isolation. Part III examines the common oversight of the duration of extreme isolation as an independent factor in Eighth Amendment constitutional review. Part IV reviews neuroscientific literature on social and environmental deprivation, starting with research on the need for social interaction and environmental stimulation for healthy brain function and mental health (Part IV.A). It then analyzes neuroscientific research on the traumatic effects of social isolation and environmental deprivation on the brain, mental and physical health, and social behavior, as well as the physical nature of social pain (Parts IV.B and IV.C). Part V uses these neuroscientific insights to develop and propose several challenges to solitary confinement. Specifically, it argues that solitary confinement inherently fails to meet the current conditions standard in three main ways: it deprives individuals of basic human needs (social interaction and environmental stimulation), it can cause serious and potentially permanent brain damage in healthy individuals, and the extent of these damages and risks is excessive compared to the prison's legitimate interests in discipline, security, and safety. Part VI further argues, from a more academic perspective, that solitary confinement and its risks are inconsistent with the retributive, incapacitative, deterrent, and rehabilitative goals of punishment. Given these arguments, the article maintains that solitary confinement is inherently cruel and unusual punishment from every relevant Eighth Amendment perspective. Part VII concludes with a proposal to abolish solitary confinement in prisons, supporting a complete rethinking of these practices under strict (and potentially uniform) time, social, and environmental standards.

SOLITARY CONFINEMENT IN "CONDITIONS JURISPRUDENCE"

The history of solitary confinement has been widely documented in existing literature. Numerous studies have also thoroughly analyzed the origins and interpretation of the Eighth Amendment. While this article does not fully review all past scholarly interpretations, it focuses on specific aspects of legal rulings regarding prison conditions and their application to solitary confinement. These aspects form the basis for the arguments presented in Part V.

Courts have not provided a definitive interpretation of "cruel and unusual punishments." However, over time, the Supreme Court has developed two methods to define the limits of such punishment. The first method, typically applied to penalties formally imposed by courts or statutes, assesses whether the punishment is proportionate to the severity of the crime committed. Thus, a punishment is considered cruel and unusual if its "excessive length or severity" is "greatly disproportioned to the offenses charged." This judgment must also consider the "evolving standard of decency that marks the progress of a maturing society."

The second method, generally applied to the treatment of incarcerated individuals and their living conditions, evaluates whether the "punishment" involves an "unnecessary and wanton infliction of pain." To determine if prison treatment or conditions cause unnecessary and wanton pain, the standard requires them to result in "serious deprivations of basic human needs" to an extent that they inflict harm or create a "substantial risk of harm" that is objectively serious (the "objective prong"). The standard also requires prison officials to be "deliberately indifferent" to the fact that such treatment or condition inflicts or risks inflicting serious harm (the "subjective prong"). Furthermore, a punishment, including the treatment and living conditions of incarcerated individuals, causes unnecessary and wanton pain, even if applied for a legitimate prison purpose, if it goes beyond what is necessary to achieve that purpose. The ultimate measure for the "unnecessary and wanton infliction of pain" standard also depends on society's evolving concepts of decency.

Despite these standards, solitary confinement itself is not inherently considered cruel and unusual punishment. However, it becomes cruel and unusual when its accompanying physical conditions lead to a wanton or unnecessary infliction of pain, based on the criteria established by the Court. Historically, courts have interpreted and applied the conditions standard narrowly in cases involving solitary confinement. This approach has drawn criticism from legal scholars who argue that courts have been "underinclusive" in their handling of solitary confinement cases. Specifically, courts have tended to downplay the general mental suffering caused by extreme isolation. As a result, the duration of solitary confinement has often been overlooked as an independent factor in constitutional evaluations. The following section will discuss each of these aspects in detail.

SOLITARY CONFINEMENT AND THE OBJECTIVE PRONG OF THE CONDITIONS STANDARD

The narrow application of the conditions standard by courts in solitary confinement cases is evident in the prevailing interpretation of "basic human need." The Supreme Court has stated that constitutional protections for prison conditions following a criminal conviction stem from the recognition that "prisoners retain the essence of human dignity inherent in all persons" and that, through incarceration, "society takes from prisoners the means to provide for their own needs." Therefore, "a prison that deprives prisoners of basic sustenance...is incompatible with the concept of human dignity and has no place in civilized society."

The concept of "basic human need" has not received a detailed or consistent interpretation from federal courts. Generally, courts have understood "basic human needs" as specific and identifiable minimum necessities for life, including food, water, shelter, exercise, medical care, and sanitation. Thus, the predominant understanding of "basic human need" mainly refers to specific "physical needs" essential for survival. Additionally, the Supreme Court has established that only "extreme deprivations" are sufficient to support a claim regarding conditions of confinement. This requirement is met when the deprivation is serious enough to deny "the minimal civilized measure of life's necessities."

The requirement of an extreme deprivation of a specific, identifiable basic human need has greatly reduced the possibility of challenging solitary confinement based on its general conditions. With few exceptions, if there is no proof that an individual in extreme isolation has been deprived of a necessary means of survival, the harsh or restrictive conditions of solitary confinement are considered insufficient to equate to a wanton and unnecessary infliction of pain.

The standard for successfully meeting the objective prong is made even higher by the requirement that the deprivation of basic human needs must either result in or pose "a substantial risk of serious harm." This requirement is evaluated by "whether society considers the risk...to be so grave that it violates contemporary standards of decency to expose anyone unwillingly to such a risk."

Courts have been unclear about whether the harm must be physical or psychological to meet this standard. However, some experts have noted that courts tend to interpret "serious harm" as "physical" harm. This understanding is based on the premise that objectively serious harm must result from a serious deprivation of specific basic human needs. As noted, these needs are generally understood to include physical necessities like food, water, medical care, shelter, or sanitation. The deprivation of such physical needs leads to harms, such as starvation, thirst, or diseases due to poor hygiene, which are fundamentally physical.

An exception to the general interpretation of "objectively serious harm" as primarily physical harm involves cases where the solitary confinement of individuals with mental disabilities has been deemed unconstitutional. This exception is based on the idea that mental illness makes individuals more vulnerable to the harmful effects of extreme isolation. A key case in this area is Madrid v. Gomez, where the federal district court compared placing mentally ill individuals in solitary confinement to "putting an asthmatic in a place with little air to breathe." Although the court acknowledged that prolonged isolation in deprived environments risks causing significant psychological trauma in incarcerated individuals without a history of mental illness, it ruled that "for many inmates, it does not appear that the degree of mental injury suffered significantly exceeds the kind of generalized psychological pain that courts have found compatible with Eighth Amendment standards." By relying on this assumption that the general prison population is resilient to the harms of extreme isolation, the court essentially maintained that extreme isolation does not pose a significant risk of serious psychological injury for all prisoners in solitary confinement. Therefore, solitary confinement is not a "per se" Eighth Amendment violation.

Cases like Madrid represent important progress in legal rulings concerning solitary confinement conditions. However, they also confirm the continued neglect of generalized mental harm or pain caused by extreme isolation among the healthy prison population. By distinguishing the risks of solitary confinement for mentally ill inmates from the general risk of psychological harm in solitary confinement, courts have failed to acknowledge that solitary confinement inherently poses dangerous psychological risks for anyone forced into isolation in deprived environments. This failure demonstrates a significant underestimation of the devastating mental effects that extreme isolation can cause in any individual.

SOLITARY CONFINEMENT AND THE SUBJECTIVE PRONG OF THE CONDITIONS STANDARD

In the Estelle and Wilson cases, the Supreme Court affirmed that Eighth Amendment claims related to confinement conditions not formally imposed as a sentence also require proof of a subjective element: the deliberate indifference of prison officials to an incarcerated person's health or safety. The "deliberate indifference" aspect of the conditions standard generally requires that a state official "knows of and disregards an excessive risk to inmate health or safety." Therefore, "the official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference." Essentially, "an official's failure to alleviate a significant risk that he should have perceived but did not...cannot under our cases be condemned as the infliction of punishment" in violation of the Eighth Amendment.

In the Farmer case, the Court clarified that deliberate indifference is equivalent to subjective recklessness, as understood in criminal law. As such, the subjective prong of the conditions standard refers to the official's blameworthy state of mind and requires proof that correctional officials knew of and disregarded a significant risk to an individual's health and safety. While the test remains specific to each case and prison official, the Court in Farmer also recognized that some risks of harm are so objectively clear that "a fact finder may conclude that a prison official knew of a substantial risk from the very fact that the risk was obvious." Therefore, proof of an official's awareness or disregard can also rely on indirect evidence that the risk was clearly and widely known but ignored.

The deliberate indifference test has faced criticism from scholars. Arguments include that this subjective element can hinder successful challenges to objectively harmful conditions of solitary confinement, as it is often difficult to prove in solitary confinement lawsuits. This difficulty is particularly evident in cases requiring proof of prison officials' deliberate indifference to the mental harm (or risk of harm) caused by solitary confinement, especially among individuals with mental illness. Prison officials are not mental health professionals and may not be aware of the symptoms or risks of a mental condition. Thus, they might avoid liability by claiming they did not have actual knowledge of a mental health need. Consequently, incarcerated individuals who report significant mental harm "face a tougher burden in proving [prison officials'] actual knowledge than their physically ill counterparts." Physical conditions are generally more easily recognized by a non-expert, and knowledge of them is easier to prove in court.

Given its questionable provability, several authors have strongly advocated for reevaluating or even eliminating the subjective prong of the conditions test, focusing solely on the objective conditions of confinement. Importantly, specifically regarding solitary confinement, some authors have highlighted that the condition of extreme isolation alone should be sufficient to presume deliberate indifference to the health and safety of the person forced into solitary confinement.

PENOLOGICAL INTERESTS

Although not an explicit part of the conditions of confinement test, the Supreme Court has stated that a factor in assessing the constitutionality of a prison condition is the state's "legitimate penological interest" in maintaining an incarcerated person in that condition. Therefore, when evaluating whether prison conditions deprive individuals of basic human needs and risk serious harm, the severity of the harm (or risk of harm) to an inmate is weighed against the prison's legitimate needs for discipline, security, and safety. Furthermore, the presence of a legitimate prison interest can influence whether prison officials were found to be deliberately indifferent to the inmate's protected interests.

Regarding solitary confinement, policymakers and correctional officials widely believe it is an effective strategy to enhance safety and promote order within the prison system by reducing criminal activity and prison violence. Therefore, the perceived necessity and effectiveness of solitary confinement in protecting prison interests supposedly outweigh its negative impact on incarcerated individuals in isolation. This implies a trade-off between the negative effects of solitary confinement on individuals, such as the loss of social interaction, and the benefits to the prison, namely discipline, security, and safety. Thus, the potential "benefits" of solitary confinement for the individual inmate, other inmates, and prison staff are seen to neutralize the harm associated with periods of extreme isolation.

This balancing argument is implicitly supported by the courts' tendency to defer to prison administrators and officials regarding solitary confinement management. Lacking established criteria for evaluating the legitimacy of a prison interest in a specific condition like solitary confinement, courts have often "defer[red] to prison officials when they claim that a particular condition or treatment is necessary." In fact, courts have openly acknowledged that prison administrators and officials have greater expertise than courts in operating prisons and understanding their dynamics. These arguments suggest that prison administrators and officials, not judges, have the most accurate understanding of available resources, know best which individuals need these resources, and are most capable of tracking incarcerated persons' evolving treatment needs. Furthermore, they possess the necessary expertise in managing safety and protection concerns that may arise in a prison setting.

This attitude of judicial deference has been particularly common in solitary confinement lawsuits. In many of these cases, even when there was a factual question about whether solitary confinement conditions posed a serious risk of substantial harm that implicated the Eighth Amendment, prison administration successfully argued a legitimate penological interest in imposing isolated confinement on an incarcerated person. For example, in Scarver v. Litscher, the Seventh Circuit acknowledged that the plaintiff experienced mental suffering due to his placement in supermax confinement, noting that he repeatedly banged his head against the cell wall. Although the court recognized this situation as concerning, it showed an unwillingness to interfere with correctional management of dangerous inmates, stating that "[p]rison authorities must be given considerable latitude in the design of measures for controlling homicidal maniacs without exacerbating their manias beyond what is necessary for security. It is a delicate balance."

According to Glidden and Rovner, while courts do not always express their opinions so openly, "a similar underlying sentiment is regularly present in such cases, and may be influencing the decision even absent any explicit language." Moreover, these and other authors have observed that prison officials are not required to fully justify the specific conditions associated with solitary confinement. Instead, general claims of safety and security often suffice as a legitimate prison interest for holding an incarcerated person in isolation. For instance, as Hafemeister and George have noted, a common justification by prison officials defending the harsh conditions of supermax facilities is that "they house the 'worst of the worst'; the violent, dangerous inmates who simply cannot be housed anywhere else." Such claims—and judicial deference to them—are frequent in Eighth Amendment analyses and have often resulted in a lack of careful scrutiny of the physical conditions of solitary confinement. Thus, even though the Supreme Court explicitly stated that the "touchstone" of the penological evaluation of prison conditions "is the effect upon the imprisoned" and that giving "deference to the findings of state prison officials in the context of the Eighth Amendment would reduce that provision to a nullity in precisely the context where it is most necessary," there is a de facto risk that the legitimate interests of prisons will take precedence over concerns about the negative consequences of harsh conditions, such as those of solitary confinement, for incarcerated individuals.

MENTAL PAIN IN EXTREME ISOLATION

Literature has extensively documented the psychological effects of solitary confinement. Numerous psychological, psychiatric, and observational studies have meticulously recorded the high number of adverse consequences of living in isolation in deprived environments for mental health, well-being, and behavior in both mentally ill and healthy populations. Suicidal thoughts, depression, and deficits in attention and memory are just a few examples of the mental distress that individuals incarcerated in extreme isolation can suffer, especially during medium to long-term isolation and in particularly deprived settings. Beyond the most severe psychological effects, psychological literature has also widely documented a link between social isolation and the experience of social pain, which involves "the painful feelings following social rejection or social loss," as well as a negative impact of social pain on physical and mental health and psychological well-being, including poor self-esteem, humiliation, a feeling of meaninglessness, greater sensitivity to rejection, and increased aggression.

Although these studies have been widely replicated and presented in courtrooms on many occasions, "lower courts have only rarely recognized grave mental harm in the context of confinement conditions, and the Supreme Court has never done so." Despite clear evidence, courts have generally been unwilling to recognize that the mental harm caused by extreme isolation is, by itself, sufficient to constitute an Eighth Amendment violation.

There are at least two main interrelated reasons for the courts' neglect of the general mental suffering caused by solitary confinement. The first concerns a tendency to dismiss social interaction as a basic human need. As noted, courts tend to interpret the "deprivation of basic human needs" requirement in terms of identifiable physical needs, such as water, food, or sanitation. Only on a few exceptional occasions have lower courts recognized social interaction as a basic human need.

The second, and resulting, reason for this neglect is that although the lack of social interaction causes serious harm, "that harm is mental, not physical." According to Jules Lobel, U.S. law views mental harm and mental pain as "a second-class citizen" compared to physical harm and pain. In principle, U.S. law has endorsed a "dualistic presumption" of harm/pain, which sees physical and mental harm/pain as qualitatively and hierarchically different types of suffering—the former being more objective, tangible, and serious than the latter.

Regarding the specific relationship of mental harm/pain to confinement conditions, Lobel has referred to the Prison Litigation Reform Act (PLRA). This federal law was enacted with the goal of reducing prison litigation in the court system by requiring incarcerated individuals to first exhaust available administrative remedies. The PLRA ultimately sought to limit the discretion of federal courts in remedial actions. In the part that regulates the requirements for filing a lawsuit, the PLRA sets an explicit physical injury prerequisite for seeking monetary compensation. Meanwhile, mental or emotional injury alone is not sufficient to support a federal civil action without evidence of physical injury.

The "physical injury versus mental and emotional pain" distinction within the PLRA provision has limited the number of lawsuits filed in federal courts over the years. Furthermore, this distinction has been echoed in cases challenging the mental anguish of solitary confinement. In fact, courts have often dismissed mental or emotional harm in the absence of proof of physical harm.

In conclusion, the general oversight of mental harm and pain following extreme isolation is closely related to and stems from a tendency to dismiss social interaction as a basic human need. Although the lack of social interaction results in serious mental pain, social interaction is a "mental need," not a physical need. Thus, unlike food and water, it does not qualify as an essential precondition for human life.

Finally, by excluding social interaction from the range of human needs warranting constitutional protection, courts have largely equated the conditions of normal confinement and solitary confinement. Based on several opinions, if the conditions of solitary confinement are substantially and materially equivalent to those of normal confinement, then the Eighth Amendment is not involved. In such cases, neither social interaction nor the mental harm/pain resulting from its deprivation are considered worthy of constitutional protection.

DURATION OF EXTREME ISOLATION

The limited importance that legal rulings on prison conditions give to mental pain is linked to another crucial aspect often overlooked in Eighth Amendment analyses of solitary confinement: the duration of extreme isolation. As mentioned in the Introduction, solitary confinement practices vary by state. Therefore, there is no uniform standard mandating a maximum amount of time an individual can spend in extreme isolation. While federal reports and national associations have issued guidelines recommending maximum time limits for solitary confinement, these limits are largely left to the discretion of prison administrations. This discretion means that solitary confinement can be open-ended, lasting for a few days, an indefinite period, or even permanently.

The Supreme Court and lower courts have rarely addressed the length of solitary confinement as an independent factor in constitutional reviews under the Eighth Amendment. Instead, they have typically considered the length of solitary confinement in conjunction with (and dependent on) the accompanying physical conditions of extreme isolation. Thus, although courts have occasionally recognized that prolonged solitary confinement may be a relevant factor in determining an Eighth Amendment violation, this factor has not been treated as an independent aspect of constitutional scrutiny.

Lower federal courts have been more willing to acknowledge the independent relevance of duration—and its effects—as an element to assess separately from the physical conditions of solitary confinement. For instance, in Sostre v. Rockefeller, the court extensively discussed the issue of duration. The district court attempted to set limits on the length of solitary confinement, stating that "to be constitutional, punitive segregation...must be limited to no more than fifteen days and may be imposed only for serious infractions of the rules." Similarly, in O’Brien v. Moriarty, the court observed that, when solitary confinement is "[i]mposed inappropriately, or for too long a period, even the permissible forms of solitary confinement might violate the Eighth Amendment."

Compared to lower courts, the Supreme Court has been more hesitant to recognize the independent constitutional relevance of the duration of solitary confinement. Instead, it has been more inclined to view duration as dependent on the accompanying physical conditions of solitary confinement. This approach is evident in Hutto. In this case, the Court followed the logic of In re Medley in ruling that solitary confinement alone "is not necessarily unconstitutional, but it may be, depending on the duration of the confinement and (emphasis added) conditions thereof... ." The Court then stated,

[i]t is perfectly obvious that every decision to remove a particular inmate from general prison population for an indeterminate period could not be characterized as cruel and unusual. If new conditions of confinement are not materially different from those affecting other prisoners, a transfer for the duration of a prisoner’s sentence might be completely unobjectionable and well within the authority of the prison administrator.

As shown in these and other passages, the Court's opinion considers the duration of solitary confinement as part of the question of whether or not solitary confinement meets constitutional requirements. However, it is only one of many factors to include in such scrutiny. Thus, the length of solitary confinement is constitutionally objectionable only when accompanying physical conditions of solitary confinement fail to meet constitutional standards.

As observed, one reason why the duration of solitary confinement does not independently fall within the scope of constitutional analysis under the Eighth Amendment stems from the excessive judicial deference to individual prison administrations in deciding and implementing solitary confinement practices. By adopting this hands-off approach, courts have largely delegated decisions about the length of solitary confinement to prison administrations. As noted, the rationale points to administrations' greater capacity to understand and address legitimate prison interests that may require imposing longer periods of isolation.

Despite this long-standing judicial attitude, broader Eighth Amendment concerns regarding long-term solitary confinement have recently reemerged in lower courts and the Supreme Court. Over the past decade, several courts have concluded that the deprivations accompanying long-term isolation do violate the Eighth Amendment. For instance, in Johnson v. Wetzel, the district court acknowledged the empirical claim that "psychological stressors such as isolation can be as clinically distressing as physical torture." Although the court did not challenge the constitutionality of solitary confinement itself, it found that the psychological deterioration a person suffers as a direct result of prolonged isolation (years in the relevant case) provides sufficient grounds for an Eighth Amendment violation.

In a similar vein, Justice Kennedy's concurring opinion in Davis v. Ayala acknowledged that extended solitary confinement raises serious constitutional questions regardless of its accompanying conditions. As such, the duration of solitary confinement alone should be subject to the Court's constitutional review under the Eighth Amendment. Equally important is Justice Kennedy's criticism of the Court's excessive deference to prison administrations. Prison officials "may have discretion" to use solitary confinement as a "temporary" measure to address protection or safety needs in prisons; nevertheless, this does not prevent courts from assessing, "within [their] proper jurisdiction and authority," the appropriateness of long-term solitary confinement given its widely documented effects on incarcerated persons and, consequently, "to determine whether workable alternative systems for long-term confinement exist, and, if so, whether a correctional system should be required to adopt them." Justice Kennedy further argued that the Court's unwillingness to address the excessive length of solitary confinement as a specific matter of constitutional review amounts to an implicit acceptance of the adverse effects that a long period of extreme isolation can have on confined individuals. Because the psychological consequences of solitary confinement have been widely established and garnered general attention and concern, failure to address them signifies an attitude of indifference.

More recently, in Apodaka v. Raemish and Lowe v. Raemish, Justice Sotomayor also expressed "deeply troubling concern" over the extreme mental pain caused by long-term isolation itself. Referencing Charles Dickens's written account of the horrors of solitary confinement in Philadelphia's Eastern State Penitentiary, Justice Sotomayor emphasized Dickens' conclusion that, in those days, penal officers were unaware of the "immense amount of torture and agony which [solitary confinement] inflict[ed] upon the sufferers." However, as Justice Sotomayor noted,

[Today] [w]e are no longer so unaware. [emphasis added] Courts and corrections officials must accordingly remain alert to the clear constitutional problems raised by keeping prisoners like Apodaca, Vigil, and Lowe in “near-total isolation” from the living world … in what comes perilously close to a penal tomb.

The recent opinions mentioned above clearly advocate for a new interpretation of the conditions standard under the Eighth Amendment. This push stems from a clear admission of the inherent inhumanity of leaving a person in extreme isolation for an excessively long time. However commendable, such recognition still misses the actual constitutional "crux" of solitary confinement, which is extreme isolation itself. The following sections specifically address this issue.

THE BRAIN IN SOLITUDE

Analysis of legal rulings on prison conditions regarding solitary confinement suggests a significant equivalence between normal confinement and solitary confinement. This equivalence arises from the fact that either type of confinement can only be challenged under the Eighth Amendment when specific accompanying physical conditions of either type fail to meet constitutional standards. Thus, the distinguishing element of solitary confinement—extreme isolation or social and environmental deprivation—is not a sufficient condition to qualify as an Eighth Amendment violation. In other words, social and environmental deprivation itself is not cruel and unusual punishment; as such, it is entirely constitutional.

Recently, a new approach has been undertaken to challenge solitary confinement under the Eighth Amendment. This approach draws on insights from social neuroscience concerning brain plasticity, social interaction, and environmental stimulation, as well as the effects of social and environmental deprivation on brain function and health. These findings have already been presented in courtrooms in several lawsuits to provide a comprehensive analysis of the impact of solitary confinement, offering additional "foundational evidence" of the harms of extreme isolation. The overarching message from social neuroscience is that the psychological deterioration following social and environmental deprivation is linked to brain alterations. These brain alterations "have implications beyond the immediately visible behaviors" and can lead to a wide range of negative psychological effects, many of which may be long-lasting or even permanent.

Although neuroscientific evidence has been used on a few occasions, it may offer new support for challenges to solitary confinement under current constitutional standards. In the following discussion, this claim is explored in more detail. The approach involves a concise review of relevant scientific insights and data—many of which have also been introduced in court cases—to highlight three main neuroscience-based challenges to solitary confinement: first, that social interaction is as much a basic physical human need as food or water; second, that social and environmental deprivation causes traumatic brain changes, which underlie potentially permanent psychological consequences; third, that social pain induced by isolation has a physical basis in the brain, making it fundamentally physical.

NECESSITY OF SOCIAL INTERACTION AND ENVIRONMENTAL STIMULATION FOR HEALTHY BRAIN FUNCTION

In Politics, Aristotle famously wrote that "man is by nature a political animal" and "a social instinct is implanted in all men by nature." Therefore, "men, even when they do not require one another's help, desire to live together." More than two millennia later, behavioral and neuroscientific disciplines have provided strong and consistent empirical data confirming that human beings are evolutionarily designed to be connected. There is now a general agreement among psychological, anthropological, sociological, and neuroscientific disciplines that social connection, interaction, and belonging are innate and universal survival needs for humans, on par with food or water.

In their influential and widely cited work, Baumeister and Leary suggested that people are programmed to form and maintain interpersonal bonds because they are motivated by an innate need to belong. Accordingly, the need to belong is an innate and universal motivation for human behavior. The authors defined this need as the drive to form and maintain strong, stable interpersonal relationships. They critically argued that this need is met by frequent human contact and genuine caring bonds between individuals.

Baumeister and Leary proposed nine criteria to assess whether a given human need is a fundamental motivation for human behavior. Specifically, the relevant need should:

(a) produce effects easily under all but adverse conditions, (b) have emotional consequences, (c) direct cognitive processing, (d) lead to negative effects (such as on health or adjustment) when frustrated, (e) elicit goal-oriented behavior designed to satisfy it (subject to motivational patterns such as object substitutability and satiation), (f) be universal in applying to all people, (g) not be derived from other motives, (h) affect a wide variety of behaviors, and (i) have implications that extend beyond immediate psychological functioning.

The authors then reviewed a large body of evidence demonstrating that belonging and social connection meet all these criteria. On this basis, they concluded that the need to belong is indeed a fundamental human need.

Various perspectives in scientific research support Baumeister's and Leary's conclusion. For example, several studies have suggested that social interaction influences the development and expression of executive functions. Additionally, social engagement and participation in meaningful social activities have reportedly helped individuals maintain their thinking skills better and delay cognitive decline in middle and older adulthood. Epidemiological studies have linked social connection and meaningful interactions with better physical and mental health, as well as reduced levels of illness and mortality. Other studies have also indicated that consistent meaningful social connections and bonds assist individuals in developing and maintaining socio-emotional skills, such as empathy and emotion regulation, which are important factors for prosocial attitudes and behavior. Importantly, these insights align with findings from studies on crime desistance.

Brain function offers one way to explain the vital importance of social connection and interaction for human beings. Following Dunbar's "social brain hypothesis," Matthew Lieberman has suggested that the brain size of different species, and specifically the size of their neocortex, corresponds to the size of their respective social environments. According to this hypothesis, humans have large brains, and the largest neocortex of all species, to meet their complex social needs. Specifically, the human brain is organized to perform social thinking to navigate complex social interactions and environmental surroundings.

In a similar vein, Daniel Siegel has proposed that the brain is a "social organ." On one hand, the brain triggers our mental processes and bodily experiences when exposed to social stimuli, thereby informing our behavioral responses toward others and contributing to our social skills and relationships. Essentially, the brain is the organ that enables social interactions, as it maintains our connections with other individuals. On the other hand, physiological and neurological reactions are directly and profoundly shaped by social interactions. Such interactions, which range from face-to-face conversations to feeling another person's touch, act as modulators, comparable to interpersonal "thermostats" that continuously shape our brain function.

Consistent with these insights, key research on brain plasticity has indicated that positive social engagement induces positive changes to the neural circuits that underpin cognitive functions, socio-emotional skills (e.g., empathy), and social behavior throughout the entire lifespan. These changes have been associated with higher cognitive performance, psychological well-being, and prosocial behavior.

Studies on social interaction and brain plasticity are related to those on the continuous influence of environmental stimulation on the brain. These studies have primarily used animal models. For instance, studies with rodents have shown that rodents raised in "enriched environments" and surrounded by their peers exhibited normal developmental pathways in the structure and function of several brain areas. These areas support a variety of functions, from typically cognitive to emotion-related functions like learning, memory, and emotion regulation. Importantly, these animal samples also exhibited normal sociable tendencies.

Several studies have hypothesized that some of these physical and functional characteristics can be explained by neurogenesis, which refers to the growth of new cells in brain regions. Evidence suggests that enriched environments "enhance cell proliferation and neurogenesis in the brain, notably in the regions critical for social interaction, memory, and communication," including the hippocampus. As discussed shortly, social and environmental deprivation appears to hinder neurogenesis in these same brain regions and leads to negative consequences at the psychological and behavioral level.

In summary, there is an inherent two-way relationship between the brain and the social environment. On one hand, the complex organization of the human brain allows humans to fulfill their biological need to connect and interact with their social world. On the other hand, the social world enables, fuels, and shapes the brain mechanisms that support the cognitive, emotional, and socially relevant abilities that allow humans to function individually and socially. Thus, social connection or interaction in enriched environments is crucial for protecting brain function and health. According to Lieberman, "[n]o one will die from lack of social contact over a few days, but people will show evidence of being in a deprived state within a short period and a lack of social connection will likely produce a wide array of negative outcomes for an individual’s mental and physical well-being before long." Therefore, when a social and environmental connection is absent, the brain, and consequently the person, will likely experience profound traumatic consequences in the long term.

THE NEUROBIOLOGICAL EFFECTS OF SOCIAL AND ENVIRONMENTAL DEPRIVATION

A large body of clinical and experimental literature has reported on the effects of solitary confinement on both healthy and unwell incarcerated populations. This literature consistently arrives at the same dramatic conclusion: solitary confinement can cause potentially permanent cognitive, emotional, and physiological damage.

For example, in his clinical observational studies, Stuart Grassian reported three main "typical features" of the general psychological effects of solitary confinement: (1) perceptual distortions, illusions, and hallucinations in various areas; (2) emotional disturbances, including anxiety and panic attacks; and (3) obsessive, intrusive thoughts, sometimes accompanied by compulsive behavior. According to Grassian, the most affected individuals may even develop psychotic disturbances with dissociative characteristics, while those less affected still experience significant psychiatric harm, including intense anxiety, obsessive thinking, agitation, paranoia, and irritability.

Grassian's findings complement those of other psychological studies that have linked life in solitary confinement to a wide range of negative psychological effects, including rage, irrational anger, fears of persecution, lack of impulse control, severe and chronic depression, loss of appetite, heart palpitations, withdrawal, and apathy, among others. This body of literature has also documented the dehumanizing effects of social isolation, which include, but are not limited to, a lack or loss of a sense of belonging, self-esteem, meaningfulness, and self-identity. The dehumanizing effects of social isolation have been associated with a higher risk of engaging in harmful, antisocial, and destructive behavior.

Notably, the literature suggests that the psychological impairments caused by solitary confinement persist even after an individual's release from prison and their return to a social environment. Specifically, individuals released back into the community after serving time in solitary confinement are "incapable of accommodating to life" due to an oversensitivity to sensory stimulations. This leads to an intolerance of typical daily noises, such as the chaos of a restaurant, and social stimulations, including an inability to participate in family moments, like eating meals together.

Scientific research has begun to identify the brain alterations that appear to correlate with the psychological effects of social and environmental deprivation (or extreme isolation). For instance, electroencephalography (EEG) studies have shown that a few days in solitary confinement can provoke brain injury-like wave alterations. Such alterations have been linked to oversensitivity to external stimuli, inadequate attention and alertness to the environment, as well as "a complete breakdown or disintegration of the identity of the isolated individual."

Clinical and experimental studies documenting the effects of solitary confinement on the brain are supported by a strong body of experimental animal research. This research is helping to understand the various brain mechanisms underlying the observed psychological and psychiatric symptoms among incarcerated individuals who have been isolated for long periods. These studies have collectively revealed that social and environmental deprivation has negative repercussions for both brain structure and function, including reduced cortical volume, diminished neuronal connections in cortical areas and the hippocampus, decreased myelin production, and altered activity in the reward system and the amygdala. These brain alterations have been connected to detachment from the environment, hostility towards others, high levels of aggression, as well as an increased risk of susceptibility to several behavioral conditions that mimic psychiatric diseases and disorders in humans, including neurodegenerative disorders and schizophrenia. Importantly, physical and functional changes in the brain can occur even after a short period of time and appear to continue after the subject is reintroduced into a social environment.

A robust body of studies has examined the neurobiological effects of chronic stress due to social and environmental deprivation. For instance, studies with rodents have revealed that rodents housed alone, unlike those housed in enriched environments, develop a smaller cerebral cortex and shorter synapses in brain areas involved in spatial information processing, memory, social information, and emotion regulation, including the hippocampus. Additionally, some studies have linked physical and functional reductions in the hippocampus with decreased hippocampal neurogenesis. These damages have been associated with long-term mental health conditions in humans, such as memory loss, cognitive decline, depression, and post-traumatic stress disorder.

Other than the hippocampus, another limbic region that appears to be impacted by social and environmental deprivation is the amygdala, which mediates emotional arousal in response to perceived stimuli. The amygdala is also involved in experiencing and processing fear and anxiety. Studies with rodents have indicated that high stress increases cortisol levels, which in turn alter neuron proliferation in the amygdala and produce adverse psychological and behavioral effects like anxiety, deficits in social interaction, and poor regulation of social behavior.

At the cortical level, studies with isolated rodents in deprived environments observed reduced levels of myelination in the prefrontal cortex. Impaired myelination in this brain area has been reported for several psychiatric illnesses, including anxiety, autism, schizophrenia, and depression. Other studies with rats have shown that isolation-reared rats exhibited reduced medial prefrontal cortex (mPFC) volume compared with group-reared rats. Among humans, reduced mPFC volume has been associated with several core symptoms of schizophrenia, such as fear of novelty, impaired memory, and sensorimotor gating.

Studies on social isolation correlate with and complement research on loneliness, which is the subjective feeling of isolation. Although loneliness is not always or necessarily linked with physical and objective isolation, such isolation can contribute to feelings of loneliness. Behavioral research on loneliness has identified perceived social isolation as a risk factor for "poorer overall cognitive performance, faster cognitive decline, poorer executive functioning, more negativity and depressive cognition, heightened sensitivity to social threats" as well as "an increased implicit vigilance for social threats along with increased anxiety, hostility, and social withdrawal; … decreased impulse control in favor of responses highest in the response hierarchy (i.e., prepotent responding); increased negativity and depressive symptomatology… ." Furthermore, several studies have highlighted links between the symptoms of loneliness and the neurobiological alterations that appear after objective social isolation.

Taken together, there is compelling evidence of the damaging and long-lasting neurobiological effects of social isolation and environmental deprivation. This evidence suggests that many of these effects are difficult to reverse, even when an individual returns to a social environment. Admittedly, many questions about the exact implications of social and environmental deprivation for the human brain and behavior remain unanswered. These include the amount of time a person can be isolated without risking irreversible damage, or how variables such as age, gender, or personal background affect the severity of social and environmental isolation on the brain and behavior. As observed, many of these questions are difficult to examine in human subjects.

While answering these questions is crucial for fully understanding the exact effects of solitary confinement on the brain and behavior, current evidence is reliable and consistent enough to support that "increased social isolation and diminished physical contact contribute to and reinforce problematic neurobiological patterns." Hence, the depriving conditions of solitary confinement will most likely "generate or exacerbate neurobiological deficits and maladaptive behaviors...[t]his becomes a significant issue, especially for individuals who are chronic offenders, where existing neurobiological vulnerabilities are intensified in settings of confinement and segregation, thereby reinforcing maladaptive patterns of behavior." In sum, neuroscience research indicates that the essential features of solitary confinement, namely social and environmental deprivation, can alone induce significant damage in the brain, all of which risks causing long-lasting or even permanent traumatic psychological and physiological consequences. So far, these consequences have been largely overlooked in courtrooms.

SOCIAL PAIN IS PHYSICAL

A key insight from social neuroscience regarding the impact of social and environmental deprivation on the brain concerns social pain. As noted, common understandings of pain and the law itself are based on the assumption that physical pain and social (mental) pain differ in their characteristics and substance. Physical pain is generally understood as pain from a bodily injury or the deprivation of a physical need; as such, it is objective, measurable, and tangible. Meanwhile, social pain is viewed as purely mental, subjective, and almost "non-existent." Therefore, it is largely dismissed as an inner experience of the individual with no tangible effects. As previously discussed, this distinction between types of pain is widespread in law and is also evident in legal rulings on prison conditions regarding solitary confinement. To challenge these traditional beliefs, a growing body of research in social neuroscience suggests that social pain is deeply rooted in the brain, making it fundamentally physical.

The most influential theory of adverse social experience, known as shared representation theory, suggests that physical pain and social pain "rely on shared neural circuitry." According to this view, the experience of social pain stems from the natural and universal human need for social connection and belonging. From an evolutionary perspective, this natural need likely originates from the lengthy period during which mammalian infants critically depend on maternal attachment, care, and nurturing for survival. The lack of these fundamental needs generates a feeling of rejection, which the individual perceives as painful and distressing. Based on this survival need, it is possible that "the social attachment system—which ensures social connection—may have piggybacked directly onto the physical pain system, borrowing the pain signal itself to indicate when social relationships are threatened." Thus, the experience of social pain can be understood as an adaptive mechanism to prevent and survive the threat of social rejection and exclusion. As Lieberman and Eisenberger put it, "[j]ust as evolution has wired us to feel pain when we lack food (e.g., hunger), water (e.g., thirst), or shelter (e.g., freezing, sunburn), perhaps evolution has wired us to feel pain when we lack...social connection."

Building on this perspective, neuroimaging research conducted by Lieberman and Eisenberger has reported a significant overlap between physical pain and social pain in the brain. Specifically, their studies have indicated that the experience of physical pain involves two distinct components: a sensory component, supported by the primary and secondary somatosensory cortex and the posterior insula; and an emotional component, namely the distressing experience of pain, supported by the dorsal anterior cingulate cortex (dACC) and the anterior insula (AI). Neuroimaging studies from this line of research have suggested that the experience of social pain activates neural pathways typically involved in the emotional component of physical pain processing—i.e., the dACC and the AI. These studies have also shown that individuals who are more sensitive to physical pain will also be more vulnerable to experiencing social pain. Interventions aimed at alleviating physical pain also appear to be effective in alleviating social pain.

Social pain has been linked to both physical and objective isolation (i.e., the actual lack of social connection) as well as perceived isolation (i.e., loneliness). Several laboratory studies within the reported line of research have explored the link between the experience of social pain and social disconnection (caused by social isolation) through neural activity in the brain regions that support the experience of this form of pain. These findings can likely explain why individuals with higher levels of objective or subjective isolation are at a greater risk of developing physical and mental health problems and even a higher risk of mortality. As Eisenberger has explained, "given that the dACC and AI are involved in responding to social disconnection, these regions may have a role in translating experiences of social disconnection into downstream physiological responses—such as heightened inflammatory activity, the immune system’s first line of defense against foreign agents and infection... ." Increased inflammatory activity has been found to relate to negative physical and mental health outcomes, including heart diseases and depression.

Finally, this line of functional magnetic resonance (fMRI) studies has also begun to investigate the effects of social pain on aggression through activation in the dACC and the AI. Preliminary results show a positive correlation between increased activity in these two brain regions (associated with the experience of social pain) and increased levels of aggression in socially rejected individuals who exhibit less executive functioning (regulatory capability). These results suggest that social pain contributes to aggressive reactions among socially rejected individuals.

In partial contrast to Eisenberger's and Lieberman's work, another fMRI study led by Tor Wager used a more detailed analysis and identified distinct neural representations of physical pain and social pain within core pain-processing brain regions and across other brain regions. Notably, this work indicates that physical pain and social pain involve independent neural representations despite common fMRI activity at the broad anatomical level (e.g., in the DACC and AI). Thus, rather than activating physical pain circuitry, social pain appears to involve different emotional representations in the brain. Based on these findings, these researchers have proposed that physical pain and social pain are ultimately distinct types of emotional experience that may lead to unique psychological consequences; therefore, they require different types of interventions. Still, the authors have highlighted that physical pain and social pain may still be functionally related and mutually influential. For instance, evidence indicates that individuals who suffered emotional trauma are at a higher risk of developing pain disorders.

Despite empirical disagreement over whether social pain is neurologically similar to physical pain, neuroscientific findings on the nature of social pain collectively offer two critical insights for this article. First, the deprivation of social connection—i.e., social isolation—leads to a range of negative emotional states, adverse psychological effects, and harmful behavioral patterns linked to the pain of being socially excluded or rejected. Second, this social pain has a physical reality in the brain. As such, it should be considered "real pain," rather than a "metaphorical pain." Importantly, the experience of social pain is not less serious or less harmful than that of physical pain. Rather, its consequences for an individual can be more distressing and damaging than those following forms of physical pain. Thus, maintaining the hierarchy of physical versus social pain by favoring the former over the latter is problematic. Most importantly, it severely overlooks the kind of suffering that social pain due to isolation can cause, which can be equally acute and equally (or even more) traumatic and long-lasting compared with the physical pain one might experience as a result of lacking a tangible, physical need.

SOLITARY CONFINEMENT IS INHERENTLY CRUEL AND UNUSUAL PUNISHMENT

The body of neuroscientific research on the vital importance of social interaction for brain structure and function, combined with insights into the damaging effects of social isolation and environmental deprivation on the brain, mind, and behavior, could revitalize challenges to solitary confinement.

While more precise empirical answers are needed to fully understand the variety and extent of solitary confinement's implications for the brain and behavior, existing evidence provides additional empirical support to challenge the core of solitary confinement: extreme isolation. As noted, insights into the traumatic consequences of extreme isolation from the neurosciences align with those from various international bodies that have emphasized that "all forms of solitary confinement without appropriate mental or physical stimulation are likely, in the long term, to have damaging effects."

Based on these insights, the remainder of this article presents three main arguments that solitary confinement, as currently practiced in many jurisdictions, inherently violates the Eighth Amendment's ban on cruel and unusual punishments. First, the core feature of solitary confinement—extreme isolation or social and environmental deprivation—fails to meet the current conditions standard. Second, there is a clear imbalance between the generalized traumatic and potentially permanent implications of social and environmental deprivation and the prison's legitimate purposes that solitary confinement is intended to serve. Furthermore, and more broadly, solitary confinement contradicts all justifications for punishment. Acknowledging that solitary confinement fails to meet any relevant Eighth Amendment requirement implies that solitary confinement is inherently unconstitutional.

FAILURE TO MEET CURRENT CONDITIONS STANDARD

The body of neuroscientific research on the effects of social and environmental deprivation on the brain provides a strong empirical basis for the argument that social and environmental deprivation (or extreme isolation)—the core of solitary confinement—qualifies as an Eighth Amendment violation under all parts of the current conditions standard. This section discusses each part in turn.

Social interaction and environmental stimulation as basic human needs

Consistent with evolutionary perspectives, neuroscientific research has provided a compelling argument for classifying social interaction as a basic human survival need, on par with other identifiable physical needs such as water, food, or shelter. As discussed, social interaction is simply inherent to human nature; humans are fundamentally social beings. This inherent nature stems from the mutual and inseparable relationship between the brain and the social environment. Furthermore, the neurobiological need for social interaction includes and is complemented by the need for environmental stimulation. As discussed, environmental stimulation significantly contributes to brain development and behavior, and the human brain must constantly receive a variety of sensory inputs from the external environment to function properly. Overall, the evidence discussed above indicates that social interaction and environmental stimulation are essential conditions for healthy brain function. As such, depriving human beings of social contact and environmental stimulation is equivalent to depriving them of their very nature.

Acknowledging the vital importance of social interaction in enriched environments implies that forcing individuals into isolation in tiny, environmentally poor cells is, by itself, sufficient to deprive them of basic human needs. Accordingly, specific physical conditions of solitary confinement (e.g., lack of heating, proper bedding, or winter clothing) should be viewed as circumstances that worsen and are therefore secondary to an underlying condition—extreme isolation—that alone is sufficient to constitute a serious deprivation of basic human needs.

Importantly, including social interaction and environmental stimulation in the range of basic human needs also challenges the courts' substantial equivalence between normal confinement and solitary confinement. As reported, courts have endorsed the view that solitary confinement is legitimate as long as its conditions, such as the provision of nutrition and shelter, are not significantly different from those affecting the general prison population. Thus, solitary confinement is not cruel and unusual as long as it guarantees the same basic human needs that are ensured to the general prison population. However, such equivalence fails to consider that extreme isolation is the condition that makes the two types of confinement materially different. This difference arises precisely from the fact that solitary confinement deprives individuals of a survival need that normal confinement guarantees. Considering this fundamental distinguishing aspect and its consequences, normal and solitary confinement cannot be placed on the same level at all. Rather, the evaluation of solitary confinement should be based on its own criteria, which should systematically recognize social interaction as a fundamental need rather than a mere privilege.

Social-environmental deprivation (extreme isolation) entails an objectively serious risk of physical harm

If the vital role of social interaction and environmental stimulation for human brain and behavior is not sufficient to establish them as basic physical needs, then evidence of the risks that social and environmental deprivation poses to the brain adds significant weight and encourages a reconsideration of the "substantial risk of serious harm" requirement in relation to solitary confinement.

As discussed, the brain changes or deteriorations that follow social and environmental deprivation appear to underlie a number of adverse cognitive, emotional, and behavioral patterns, and they have also been reported in major psychiatric disorders, including depression and schizophrenia. These findings support and corroborate the existing robust body of psychological studies that have documented the dramatic psychological and psychiatric effects of solitary confinement. Moreover, the brain and psychological damage due to social and environmental deprivation have been found to contribute to physical health problems and even increase the risk of mortality. From this perspective, the disfiguring damage that solitary confinement could inflict on incarcerated individuals can be long-lasting or even permanent.

Equally important are insights into the nature and implications of social pain caused by social isolation. Besides indicating that social pain has physical reality, neuroscientific research has crucially suggested that the experience of social pain can be far worse than that of physical pain in many respects. Social pain has been linked to a series of psychological symptoms, including humiliation, low self-esteem, maladaptive actions, including aggression, and lower levels of physical and mental health, especially in the long term. Thus, even if the traumatic effects of social pain are not immediately visible, they may manifest and grow over time.

By translating neuroscientific insights into the language of legal rulings on prison conditions, one may make the following observations. First, social and environmental deprivation does entail an objectively serious risk of physical harm that is comparable to food or sleep deprivation. Even if the harm that solitary confinement imposes on the brain translates into mental deterioration, and is therefore mental, it is also undeniable that "the type of severe psychological deterioration observed in solitary confinement is due to physical harms imposed on the brain." As such, it is ultimately physical.

Second, the harm that solitary confinement imposes on the brain underlies a number of long-lasting or potentially permanent mental, physical, and physiological conditions. Therefore, the possible harms of solitary confinement are not only disfiguring but also potentially permanent. Finally, and perhaps most importantly, the risk of such physical harms can manifest even after a short period of extreme isolation. As mentioned, (neuro)science has not yet precisely determined how long an individual can spend in isolation without incurring irreversible brain damage. However, there is a consensus across scientific disciplines (including neuroscience) that the amount of time an individual spends in socially and environmentally deprived conditions positively correlates with the degree of risk that they will deteriorate neurologically, physiologically, psychologically, and physically.

Admittedly, not all individuals will necessarily and inevitably suffer irreversible damage, and not everyone will experience the same kinds of trauma after the same amount of time. However, as Bennion has correctly noted, "[t]he fact that serious risks may never materialize in serious harm (or that harm may not be imminent) is not conclusive for...the test." Furthermore, the risk of undergoing serious brain and mental deterioration following solitary confinement is universal: any person is vulnerable to such risk, regardless of their history of mental illness.

In view of the above insights, solitary confinement alone also meets the "substantial risk of serious (physical) harm" requirement of the objective prong of the conditions standard. By depriving individuals of a minimal life necessity, solitary confinement inherently risks inflicting unnecessary suffering characterized by disfiguring and potentially permanent consequences. As the Court has repeatedly stated, the Eighth Amendment's interpretation changes in line with the knowledge and standards of decency of an evolving society. A punishment that risks inflicting disfiguring and potentially permanent damage upon individuals exceeds contemporary standards of decency, and no civilized society should tolerate such a toll on human beings.

Deliberate indifference follows from extreme isolation

As noted above, the subjective prong of the conditions standard has been subject to scholarly criticism, especially in solitary confinement cases. It can be extremely difficult to prove that prison personnel or administrators were deliberately indifferent to the harms inflicted upon incarcerated individuals by a serious deprivation of basic human needs. Such challenging proof can hinder the success of legitimate Eighth Amendment claims based on harmful conditions of solitary confinement.

Courts have admitted that when the risk of serious harm from a confinement condition is objective and generally known, such objective proof is also sufficient to infer the culpable state of mind of prison personnel. Regarding solitary confinement, several court opinions have questioned the necessity of explicit proof of deliberate indifference on the grounds that placing prisoners in solitary confinement poses a substantial risk of serious harm. For instance, the court in Wilkerson observed that "basic common sense indicates that 'lack of exercise, social isolation, and/or stress are associated with [deleterious] conditions'....[Therefore, a] court 'may infer the existence of this subjective state of mind [i.e., deliberate indifference] from the fact that the risk of harm is obvious'." Likewise, opinions in Supreme Court cases have emphasized the growing awareness of the damages of solitary confinement in modern American penal systems. Such damages have been extensively documented and acknowledged by scientific, legal, and international sources.

Furthermore, several authors have supported a presumption of culpability for prison officials in cases seeking injunctions. For instance, it has been suggested that "prisoners could certainly show by the time of trial that authorities were aware of either the actual harm or risk of harm caused by solitary confinement." Thus, when harmful conditions are allowed to persist, courts may infer the culpable mindset of prison officials from the conditions themselves without also requiring explicit proof of intent.

The thesis of this article further integrates and strengthens these claims. When acknowledging that the core condition of solitary confinement, namely extreme isolation, itself amounts to a wanton and unnecessary infliction of pain and constitutes cruel and unusual punishment, the subjective prong of the test loses its purpose and becomes unnecessary. Given the growing general awareness of the objective damages linked with solitary confinement, proof of social and environmental deprivation is sufficient to infer that prison officials acted with deliberate indifference, as extremely isolating an incarcerated person is essentially depriving them of a basic human need and entails an objectively serious and well-known risk of harm. Therefore, a fact-finder could conclude that by keeping an incarcerated person in solitary confinement despite the obvious health risks, both physical and psychological, the prison staff acted with deliberate indifference to the substantial risk of consequent harm.

FAILURE TO MEET THE INTENDED PENOLOGICAL AIMS

The evidence presented regarding the widespread consequences of solitary confinement also challenges the supposed balance between the "pains" of solitary confinement and the legitimate prison interests of discipline, security, and safety. This "newly" emerging imbalance stems from the fact that social and environmental deprivation, especially when prolonged, risks causing severe brain deterioration, even in individuals without a history of mental illness. Such deterioration may not be limited to the period of isolation; given the long-lasting psychological consequences they entail, the effects of such deterioration risk continuing even after an individual is reintroduced into a social environment, whether it is the prison or the general community. The risk of undergoing brain damage due to extreme isolation is an excessive—and, therefore, extremely unbalanced—cost for any legitimate prison interest to supposedly justify it.

These claims mutually reinforce the robust body of evidence documenting that neither short-term nor long-term stays in solitary confinement achieve specific deterrent effects by reducing subsequent disciplinary infractions or prison incidents. Rather, evidence shows that stays in solitary confinement appear to produce the opposite effect. Moreover, jurisdictions that have restricted the use of solitary confinement have seen a decrease in prison violence. Thus, limiting the use of solitary confinement does not undermine the ability of prison administrators to control the prison population or maintain safety and may actually increase it.

Acknowledging these claims may prompt courts to reconsider their (often excessive) deference to prison administrations regarding the management and application of solitary confinement practices. Specifically, it may prompt courts to carefully scrutinize the "legitimate penological justifications" that prison administrations cite to defend their use of solitary confinement. Thereby, it could fully activate the constitutional protection of individuals in custody that is central to the Eighth Amendment.

From a broader perspective, evaluating the legitimate justifications for a given prison condition or correctional practice under the Eighth Amendment must consider the progress of knowledge as it reflects the evolution of society and its standards of decency. Currently, there is a general consensus among domestic and international bodies that disfavors solitary confinement, suggesting that standards of decency have moved away from using solitary confinement to serve its intended prison purposes. Increased knowledge also reflects (the reasons for) the higher effectiveness of less restrictive and less painful methods to serve identical prison purposes. Thus, no prison interest can justify the systematic and indiscriminate use of solitary confinement. Moreover, no prison interest can counterbalance the damage that solitary confinement risks inflicting on incarcerated individuals. Admittedly, solitary confinement may still be warranted in instances requiring an individual's temporary protection or for the most serious, violent offenses or infractions, though only when other measures have been tried without satisfactory results. Even in such instances, separating an individual from the rest of the prison community can still be managed in a more humane and less restrictive way.

THE ANTITHESIS BETWEEN SOLITARY CONFINEMENT AND THE GOALS OF PUNISHMENT

Solitary confinement and its effects are also inconsistent with the retributive, incapacitative, deterrent, and rehabilitative goals of punishment. As such, it lacks any purpose within the penal system. Although this broader perspective on punishment is uncommon in Eighth Amendment analyses in (solitary) confinement cases, exploring why solitary confinement contradicts each dominant justification for punishment still offers academic value.

Beginning with retribution, retribution-based analyses generally include two components. The first, which is objective, evaluates a punishment based on the seriousness of the crime committed, while the second, which is subjective, evaluates a punishment based on the degree of blameworthiness of the perpetrator. Evaluations of blameworthiness also consider the individual characteristics of a perpetrator, including their age or mental capabilities. Therefore, from a retributive perspective, a punishment is disproportionate when it is excessively severe relative to the crime and the perpetrator's overall degree of blameworthiness and, consequently, culpability.

For the purposes of this article, solitary confinement is measured against another critical aspect of retributive theory: the preservation and respect for the moral rationality of perpetrators. The premise of moral rationality is undeniably central to any retributive punishment. Retribution assumes that the perpetrator is a rational moral agent capable of understanding the meaning and consequences of their actions and freely chooses to act unlawfully. Based on this assumption, retributive punishment aims to ensure that perpetrators are "capable of understanding the wrongs they have committed and the fairness of the penal sanctions imposed on them by the state in response to those wrong." Accordingly, retributivism insists on structuring legal punishment so that it is, at minimum, consistent with treating offenders as rational moral beings.

Retributivism requires that incarceration deprives perpetrators of their freedoms by drastically reducing their privileges to live autonomous lives. However, retribution does not require that incarceration also erodes the capacities that constitute moral personhood, such as "physical and psychological health, work and interaction with others." From a retributive perspective, these capacities and dispositions need to be regularly exercised to preserve the ability of incarcerated individuals "to comprehend and respond constructively to the reasons for which they are being punished."

From this line of reasoning, solitary confinement does not align with this fundamental aspect of retributive punishment. Solitary confinement risks inflicting traumatic brain and mental damage on incarcerated individuals, all of which compromise the cognitive and emotional abilities that support practical reasoning skills, and "cause further atrophy of what may have already been weak capacities to identify with and feel for others." Furthermore, the long-lasting or even permanent physiological, mental, and physical damage that solitary confinement can cause may persist even after an incarcerated person has served their sentence. Therefore, solitary confinement, which can inflict long-lasting or even permanent losses on perpetrators, makes a prison sentence disproportionate to the seriousness of the crimes committed. Such an outcome is simply contrary to any mainstream retributive perspective.

Solitary confinement also fails to meet the consequentialist goals of punishment, namely incapacitation, deterrence, and rehabilitation. Incapacitation refers to how punishment, especially incarceration, prevents perpetrators from committing further offenses by physically removing them from society. Solitary confinement, particularly in supermax facilities, serves this purpose during the period of confinement. However, the benefit of this incapacitation argument for public safety requires an additional analysis of the specific deterrent effects of solitary confinement.

Theories concerning the use of solitary confinement emphasize its potential to deter future crime. However, empirical evidence disproves the effectiveness of solitary confinement as a tool to prevent reoffending or change the behavior of incarcerated individuals. There is evidence that prisoners in solitary confinement at supermax prisons fare even worse than prisoners in the general population once they are released. For instance, an epidemiological study by Maers and Bales compared recidivism rates among individuals who had been in solitary confinement with those of individuals who had been normally confined. They found that solitary confinement was associated with a higher risk that formerly incarcerated individuals would commit a violent crime after being released. Other epidemiological studies have replicated this finding. The reasons for the increased risk of reoffending also largely stem from the brain alterations due to solitary confinement, which have been associated with adverse psychological symptoms and mental health issues known to be risk factors for socially dysfunctional behaviors, including antisocial conduct.

Finally, solitary confinement does not serve the rehabilitative ideal of punishment. (Social) rehabilitation clearly aims to reintegrate convicted persons into society upon their release so they can lead a law-abiding and self-supporting life. Thus, it seeks to reestablish positive relationships between perpetrators and the rest of society by facilitating (self-)reform and change based on relational processes. Rehabilitation crucially promotes as much inclusiveness and positive social engagement as possible while perpetrators serve their sentence, as this can facilitate their social reintegration into the community.

In addition to opposing the core values and aims of rehabilitation theory, the potential harms of solitary confinement, including a greater predisposition to aggression and other harmful psychological and behavioral patterns, can seriously compromise an individual's social functioning. Therefore, these harms significantly hinder the rehabilitation and re-socialization process, making it more difficult, if not nearly impossible in some cases.

In conclusion, the type and extent of harm that solitary confinement can inflict on individuals do not align with and are therefore disproportionate to any justification for punishment. Given this, solitary confinement constitutes an unnecessary and wanton infliction of pain because it not only deprives individuals of their basic social and environmental biological needs but also lacks any meaningful justification from a penal perspective. The suffering that solitary confinement imposes is unnecessary and violates any relevant perspective under the Eighth Amendment. No penal interest or aim can justify its infliction; solitary confinement is, in and of itself, cruel and unusual punishment.

A PATH FORWARD: ABOLISHING SOLITUDE IN PRISON

The arguments presented in this article ultimately support the conclusion that solitary confinement, as it is still administered in a number of facilities or penal systems, should be completely eliminated. This conclusion aligns with the wide array of domestic and international organizations, movements, and associations that have called for abolishing solitary confinement or at least restricting its use to exceptional and strictly regulated circumstances.

Separating an incarcerated person from the rest of the prison population should always be a last resort intervention, used only for extreme cases—which must be properly documented by prison personnel and potentially overseen by specialized committees—when absolutely necessary to achieve legitimate prison goals. In such cases, the separation of an individual from the rest of the prison community should be subject to strict time, social, and environmental standards. These (possibly uniform) standards are needed to counteract most arbitrarily employed forms of solitary confinement as well as a constitutional weakness that allows prison administrations to use solitary confinement with minimal judicial oversight.

Regarding time limits, the ASCA-Liman survey reported time intervals ranging from between 1 and 30 days to more than six years across jurisdictions. Although fewer individuals were kept in solitary for 1–30 days, higher percentages were reported for periods in solitary of at least one month to over six years.

More empirical research is needed to determine the exact maximum time limit for depriving an individual of constant social contact without causing irreversible damage. Nevertheless, acknowledging that such deprivation risks causing or worsening physical, physiological, and psychological adverse effects even after just a few days provides sufficient grounds for adopting uniform maximum time limits that align with existing empirical knowledge and domestic and international guidelines. Given the current lack of legal rulings on duration limits for solitary confinement, the strength of international and domestic guidelines mandating a maximum of 15 days of solitary confinement should be used as a benchmark to set uniform time standards in all jurisdictions. All states should adhere to these standards, with any violation constituting an Eighth Amendment violation.

In addition to setting uniform time limits on solitary confinement, uniform sociability standards are also warranted. The ASCA-Liman survey has further reported positive data from a number of jurisdictions that have implemented specific policies in recent years to restrict the use of solitary confinement to the most objectively serious cases in order to improve the "social" conditions of individuals housed in solitary cells. Several jurisdictions have implemented policies that allow for more time out of the cell, outdoor recreational activities, classes, job training, rehabilitation, and re-entry programs for restricted individuals. However, only a few of them have increased time for visitors. Some policies even offer training for correctional officers to learn alternative responses to prison violence that focus on dialogue, accountability, and cooperation. Notably, statistics reflect that both prison incidents and the overall rate of recidivism upon re-entry to the community have decreased. These scattered changes are encouraging and illustrate a growing acknowledgment that solitary confinement is counterproductive and can be extremely damaging. Ensuring that all correctional facilities adopt and apply sociability standards—including recreation, education, rehabilitation programs, and visiting hours with significant others—for prisoners who are temporarily separated from the rest of the community is crucial to counteract the side effects of isolation as well as aid in their social rehabilitation and re-entry process.

Finally, although this suggestion applies to correctional facilities in general, the design of separation cells should follow strict environmental standards. On several occasions, the Court stressed that "the Constitution does not mandate comfortable prisons." However, it also stated that the Constitution "neither does...permit inhumane ones." The empirical studies reported above indicate that environmental surroundings—whether enriched or deprived—significantly influence brain structure and function, as well as psychological well-being and social behavior. Tiny and environmentally deprived cells risk worsening the negative effects of a lack of social interaction.

Several authors have called for making correctional facilities as humanized and home-like as possible. Positive international examples indicate that home-like cells with natural light, even in maximum security facilities, where prisoners are provided amenities such as proper bedding, furniture, or reading materials, contribute to prisoners' physical and psychosocial well-being. Such generalized well-being has been found to positively contribute to reduced institutional misconduct and overall recidivism.

It is admittedly difficult to expect such a dramatic change in U.S. facilities in the immediate future. Nevertheless, it is imperative to acknowledge that such realities exist and are effective. Most importantly, those realities convey an important lesson of "dignity and humanity that is the birthright of every person, and...respect [for] the collective dignity and humanity of society." These are the values and rights that inspire the Eighth Amendment and should accordingly inspire the abolition of solitary confinement.

CONCLUSION

In the opening paragraph of her dissenting opinion in Apodaca, Justice Sotomayor wrote, "A punishment need not leave physical scars to be cruel and unusual." However, social and environmental deprivation can apparently leave many scars, which may be visible and tangible. Solitary confinement is a disfiguring and dehumanizing punishment, as it deprives people of their biological needs, drastically changes their physiology, and causes severe psychological and physical harm. It is increasingly an appropriate time to address the many, potentially incurable scars that solitary confinement can inflict on incarcerated individuals. Continuing to ignore these scars can only make them even more profound.

Introduction

Solitary confinement in the United States is widely known, with official reports, legal and psychological writings, and news stories detailing how imprisoned people are forced into extreme isolation. This isolation can last for hours or for unknown periods, with little to no social contact beyond brief interactions with prison guards, often in poor living conditions. While this situation exists in many correctional facilities, solitary confinement is still considered a valid practice. It is thought to help prisons maintain discipline, security, and safety.

There are no uniform rules or ways solitary confinement is managed across states. Instead, policies and practices are mostly left up to each prison system. This lack of consistent rules has often led to misuse of solitary confinement, sparking national and international calls to either stop the practice or significantly change it. These efforts have led to some reforms in certain areas, as well as recommendations from the Department of Justice and national groups. These suggestions encourage limiting solitary confinement by setting maximum time limits or by banning its use for vulnerable groups, such as people with mental disabilities and young individuals.

However, progress in limiting or improving solitary confinement has been slow and often inconsistent. A report from the American State Correctional Association and Liman Center (ASCA-Liman) shows that the number of people in isolation has decreased in some states but increased in others.

Beyond the lack of consistent rules, the constitutional standard for solitary confinement under the Eighth Amendment, which bans cruel and unusual punishments, is applied narrowly and with much deference. The Supreme Court has stated that prison conditions, including solitary confinement, are cruel and unusual if they cause "unnecessary and wanton infliction of pain" on incarcerated people. This happens when conditions involve denying "basic identifiable human needs" to the point of causing harm or a "substantial risk of serious harm," and when prison staff act with "deliberate indifference." While not an explicit rule, courts also consider a state's "legitimate penological interest" in keeping a prisoner in such a condition when deciding if it is constitutional.

Specifically regarding solitary confinement, courts, with few exceptions, have continued to apply this standard narrowly. They have often downplayed the general mental pain caused by living in isolation in restrictive cells. As a result, they have frequently ignored how long solitary confinement lasts as a separate issue for constitutional review. In doing so, courts have often overlooked the impact of extreme isolation, also called social and environmental deprivation, which is what makes solitary confinement different from regular confinement.

Recently, a new way to challenge solitary confinement has emerged. This approach uses findings from social neuroscience about the damaging and potentially lasting effects of social and environmental deprivation on the brain. Research in social neuroscience suggests that social interaction in stimulating environments is crucial for normal brain function and mental health. Further studies have revealed various brain damages that can occur even after a short period of social and environmental deprivation. These damages have been linked to several potentially irreversible mental health conditions. Additionally, many mental conditions related to these damages from isolation in deprived environments have been connected to an increased risk of harmful actions and socially dysfunctional behaviors, including aggression. Another important area of research from this field has shown that social pain from isolation is a real, physical experience.

Neuroscientific findings on the harmful effects of social and environmental deprivation support and strengthen the many studies on the negative psychological impacts of solitary confinement. They also offer new grounds to challenge solitary confinement. First, these studies support the idea that solitary confinement itself denies individuals basic human needs: social interaction and environmental stimulation. Second, there is a risk of physical brain damage within days of isolation in a deprived setting. Third, the resulting harm to mental health and behavior could continue even after the person returns to a social environment, potentially affecting their long-term social functioning. Based on these insights, this article argues that solitary confinement is inherently cruel and unusual under any aspect of the current conditions standard. It also suggests ways to fundamentally rethink solitary confinement practices.

Solitary Confinement in "Conditions Jurisprudence"

The history of solitary confinement and the evolution of the Eighth Amendment have been widely discussed in existing literature. While this article does not fully review these extensive accounts, it focuses on specific aspects of the law regarding prison conditions and how they apply to solitary confinement. These aspects form the basis for the arguments presented later in the article.

The term "cruel and unusual punishments" has not been definitively interpreted by courts. However, over time, the Supreme Court has developed two ways to define what constitutes cruel and unusual punishment. The first approach, generally used for punishments formally given by courts or laws, assesses whether the punishment is proportionate to the crime committed. A punishment is considered cruel and unusual if its "excessive length or severity" is "greatly disproportioned to the offenses charged." This judgment must consider "the evolving standard of decency that marks the progress of a maturing society."

The second approach, generally applied to how people are treated in prison, including their living conditions, examines whether the "punishment" causes "unnecessary and wanton infliction of pain." To determine if prison treatment or conditions cause such pain, they must result in clear and "serious deprivations of basic human needs" to an extent that they cause harm or create a "substantial risk of harm" that is objectively serious (the "objective prong"). The standard also requires that prison officials show "deliberate indifference" to the fact that such treatment or condition causes or risks causing serious harm to the individual (the "subjective prong"). Furthermore, a punishment, including how prisoners are treated and their living conditions, causes unnecessary and wanton pain even if it aims for a legitimate prison goal, if it goes beyond what is necessary to achieve that goal. The ultimate measure for the "unnecessary and wanton infliction of pain" standard also relies on the developing ideas of decency in an evolving society.

Despite these standards, solitary confinement itself is not automatically considered cruel and unusual punishment. It "becomes" cruel and unusual when its material conditions cause wanton or unnecessary pain according to the criteria set by the Court. Historically, courts have interpreted and applied the conditions standard narrowly in solitary confinement cases. This approach has drawn criticism from legal scholars who argue that courts have been "underinclusive" by tending to disregard the general mental pain caused by extreme isolation. As a result, they have often overlooked the duration of solitary confinement as a separate factor for constitutional review. The following sections will discuss these aspects in detail.

Solitary Confinement and the Objective Prong of the Conditions Standard

The narrow way courts apply the conditions standard to solitary confinement cases first comes from how they mostly interpret "basic human need." The Supreme Court has broadly stated that constitutional protections for prison conditions after a conviction come from recognizing that "prisoners retain the essence of human dignity inherent in all persons." Also, through imprisonment, "society takes from prisoners the means to provide for their own needs." Therefore, "a prison that deprives prisoners of basic sustenance... is incompatible with the concept of human dignity and has no place in civilized society."

Federal courts have not offered a detailed or consistent interpretation of "basic human need." Generally, courts have understood "basic human needs" as specific and identifiable minimum necessities for life, such as food, water, shelter, exercise, medical care, and sanitation. So, the main understanding of "basic human need" focuses mostly on specific "physical needs" considered essential for survival. Additionally, the Supreme Court has ruled that only "extreme deprivations" are enough to support a claim about prison conditions. This requirement is met when the deprivation is serious enough to deny "the minimal civilized measure of life's necessities."

The demand for an extreme deprivation of a specific, identifiable basic human need has greatly reduced the ability to challenge solitary confinement based on its general conditions. With few exceptions, if there is no proof that a person in extreme isolation has been denied a necessary means of survival, then harsh or restrictive solitary confinement conditions are not considered enough to be a wanton and unnecessary infliction of pain.

The standard for successfully meeting the objective part of the conditions test becomes even higher with the requirement that the deprivation of basic human needs must either cause or create "a substantial risk of serious harm." This requirement is judged by "whether society considers the risk... to be so grave that it violates contemporary standards of decency to expose anyone unwillingly to such a risk."

Courts have been unclear about whether the harm must be physical or psychological to meet the standard. However, some experts have noted that courts tend to view "serious harm" as "physical" harm. This understanding assumes that objectively serious harm must come from a serious denial of specific basic human needs. As mentioned earlier, these needs are generally seen as physical, including food, water, medical care, shelter, or sanitation. The denial of these physical needs leads to harms—like starvation, thirst, or diseases from poor hygiene—that are fundamentally physical.

The exception to interpreting "objectively serious harm" as mainly physical harm comes from cases that have found solitary confinement of people with mental disabilities to be unconstitutional. This exception is based on the idea that mental illness makes people more vulnerable to the harmful effects of extreme isolation. A key case in this area is Madrid v. Gomez, where a federal district court compared putting mentally ill people in solitary confinement to "putting an asthmatic in a place with little air to breathe." Although the court recognized that long-term isolation in poor environments risks causing significant psychological trauma even in incarcerated people without a history of mental illness, it stated that "for many inmates, it does not appear that the degree of mental injury suffered significantly exceeds the kind of generalized psychological pain that courts have found compatible with Eighth Amendment standards." By relying on this assumption that most prisoners are resilient to the harms of extreme isolation, the court essentially maintained that extreme isolation does not pose a significant risk of serious psychological injury for all prisoners in solitary confinement. Therefore, solitary confinement is not an automatic Eighth Amendment violation.

Cases like Madrid represent important progress in the legal understanding of solitary confinement conditions. However, they also confirm the ongoing neglect of general mental harm or pain caused by extreme isolation among the healthy prison population. By distinguishing the risks of solitary confinement for mentally ill prisoners from the general risk of psychological harm caused by solitary confinement, courts have failed to recognize that solitary confinement inherently involves dangerous psychological risks for anyone forced into isolation in restrictive environments. This failure shows a significant underestimation of the devastating mental effects that extreme isolation can have on any individual.

Solitary Confinement and the Subjective Prong of the Conditions Standard

In Estelle and Wilson, the Supreme Court decided that claims under the Eighth Amendment about prison conditions not formally part of a sentence also need proof of a subjective element. This means showing that prison officials were deliberately indifferent to a prisoner's health or safety. The "deliberate indifference" part of the standard generally requires that a state official "knows of and disregards an excessive risk to inmate health or safety." Therefore, "the official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference." Essentially, "an official’s failure to alleviate a significant risk that he should have perceived but did not... cannot under our cases be condemned as the infliction of punishment" that violates the Eighth Amendment.

In Farmer, the Court clarified that deliberate indifference is the same as subjective recklessness, as understood in criminal law. Thus, the subjective part of the conditions standard refers to the official's blameworthy state of mind and requires proof that correctional officials knew about and ignored a serious risk to an individual's health and safety. While this test is tailored to each case and prison official, the Court in Farmer also acknowledged that some risks of harm are so clear that "a fact finder may conclude that a prison official knew of a substantial risk from the very fact that the risk was obvious." Therefore, proof of the official's awareness or disregard can also come from circumstantial evidence showing the risk was clearly and widely known but ignored.

The deliberate indifference test faces criticism from scholars. Arguments include that this subjective element can make it harder to successfully challenge harmful solitary confinement conditions, as it is often difficult to prove in legal cases involving solitary confinement. This difficulty is especially clear in cases requiring proof of prison officials' deliberate indifference to the mental harm (or risks of harm) caused by solitary confinement, particularly among people with mental illness. Prison officials are not trained in mental health and may not know the symptoms or risks of a mental condition. Thus, they might avoid responsibility by simply claiming they were not actually aware of a mental health need. As a result, prisoners who report significant mental harm "face a tougher burden in proving [prison officials'] actual knowledge than their physically ill counterparts." It is true that physical conditions are more easily recognized by non-experts, and proving knowledge of them is easier in court.

Given how difficult it is to prove, several authors have strongly called for rethinking or even removing the subjective part of the conditions test and focusing only on the objective prison conditions. Importantly, regarding solitary confinement specifically, some authors have pointed out that the condition of extreme isolation alone should be enough to assume deliberate indifference to the health and safety of the person forced into solitary confinement.

Penological Interests

Although not an explicit criterion for assessing prison conditions, the Supreme Court has stated that a factor to consider when evaluating the constitutionality of a prison condition is the state's "legitimate penological interest" in keeping a prisoner in that condition. Therefore, when assessing whether one or more prison conditions deprive individuals of basic human needs and risk causing serious harm, the severity of the harm (or risk of harm) to an inmate is weighed against the prison's legitimate needs for discipline, security, and safety. Furthermore, the presence of a legitimate prison interest can influence whether prison officials were found to be deliberately indifferent to the inmate's protected interests.

Regarding solitary confinement, policymakers and correctional officials widely believe that using solitary confinement is an effective way to improve safety and maintain order throughout the prison system because it reduces criminal activity and prison violence. Therefore, the supposed necessity and effectiveness of solitary confinement in protecting prison interests are thought to outweigh its negative impact on prisoners forced into isolation. This implies a trade-off between the negative effects of solitary confinement on prisoners—such as the loss of social interaction—and the benefits for the prison, namely discipline, security, and safety. Thus, the potential "benefits" of solitary confinement for the individual inmate, other inmates, and prison staff are seen as neutralizing the harm associated with stays in extreme isolation.

This balancing argument is implicitly supported by courts' tendency to defer to prison administrators and officials in managing solitary confinement. Without clear standards for evaluating the legitimacy of a prison interest in a specific condition like solitary confinement, courts have often "defer[red] to prison officials when they claim that a particular condition or treatment is necessary." In fact, courts have explicitly recognized that prison administrators and officials are more competent than courts in running prisons and understanding their dynamics. These arguments suggest that prison administrators and officials, not judges, have the best understanding of available resources, know which individuals most need these resources, and are best able to track prisoners' changing treatment needs. Moreover, they have the right expertise to manage safety and protection needs that may arise in a prison setting.

This attitude of judicial deference has been especially common in solitary confinement lawsuits. In many of these cases, even if there was a factual question about whether solitary confinement conditions posed a serious risk of substantial harm that violated the Eighth Amendment, prison administration still successfully claimed a legitimate prison interest in isolating a prisoner. For example, in Scarver v. Litscher, the Seventh Circuit acknowledged that the plaintiff had suffered mental distress due to his placement in supermax confinement, noting that he had repeatedly banged his head against the cell wall. Although the court recognized this situation was concerning, it showed an unwillingness to interfere with correctional management of dangerous inmates and ruled that "prison authorities must be given considerable latitude in the design of measures for controlling homicidal maniacs without exacerbating their manias beyond what is necessary for security. It is a delicate balance."

According to Glidden and Rovner, while courts do not always state their opinions so openly, "a similar underlying sentiment is regularly present in such cases, and may be influencing the decision even absent any explicit language." Furthermore, these and other authors have observed that prison officials are not required to fully justify the specific conditions that accompany solitary confinement. Instead, general claims of safety and security often suffice as a legitimate prison interest for holding a prisoner in isolation. For instance, as Hafemeister and George have noted, a common justification offered by prison officials to defend the harsh practices in supermax facilities is that "they house the 'worst of the worst'; the violent, dangerous inmates who simply cannot be housed anywhere else." Such claims—and judicial deference to them—are common in Eighth Amendment analyses and have often led to a lack of careful examination of the actual conditions of solitary confinement. Thus, even though the Supreme Court stated that the "touchstone" for evaluating prison conditions is "the effect upon the imprisoned" and that granting "deference to the findings of state prison officials in the context of the [E]ighth [A]mendment would reduce that provision to a nullity in precisely the context where it is most necessary," there is still a risk that the legitimate interests of prisons will outweigh concerns about the negative consequences of harsh conditions, such as solitary confinement, for incarcerated people.

Mental Pain in Extreme Isolation

Extensive literature has detailed the psychological effects of solitary confinement. Many psychological, psychiatric, and observational studies have thoroughly documented the significant negative consequences of living in isolation in deprived environments on mental health, well-being, and behavior in both mentally ill and healthy populations. Suicidal thoughts, depression, and problems with attention and memory are just a few examples of the mental anguish that people in extreme isolation can suffer, especially during medium to long periods of isolation and in particularly restrictive settings. Beyond the most severe psychological effects, psychological literature has also widely documented a link between social isolation and the experience of social pain, which involves "the painful feelings following social rejection or social loss," as well as a negative impact of social pain on physical and mental health and psychological well-being, including low self-esteem, humiliation, a feeling of meaninglessness, increased sensitivity to rejection, and increased aggression.

Although these studies have been widely replicated and frequently brought into courtrooms, "lower courts have only rarely recognized grave mental harm in the context of confinement conditions, and the Supreme Court has never done so." Despite clear evidence, courts have generally been unwilling to acknowledge that the mental harm caused by extreme isolation is, by itself, enough to violate the Eighth Amendment.

There are at least two main, interconnected reasons why courts neglect the general mental suffering caused by solitary confinement. The first is a tendency to dismiss social interaction as a basic human need. As noted, courts tend to interpret the requirement of "deprivation of basic human needs" as referring to identifiable physical needs, such as water, food, or sanitation. Only in a few exceptional cases have lower courts recognized social interaction as a basic human need.

The second, and resulting, reason for this neglect is that although the lack of social interaction causes serious harm, "that harm is mental, not physical." According to Jules Lobel, U.S. law views mental harm and mental pain as "a second-class citizen" compared to physical harm and pain. In principle, U.S. law has adopted a "dualistic presumption" of harm/pain, which sees physical and mental harm/pain as qualitatively and hierarchically different types of suffering—with the former being more objective, tangible, and serious than the latter.

Regarding the specific connection of mental harm/pain to confinement conditions, Lobel has pointed to the Prison Litigation Reform Act (PLRA). This federal law was passed to reduce the number of prison lawsuits by requiring prisoners to first use all available administrative remedies. Ultimately, the PLRA aimed to limit the power of federal courts in taking corrective action. In the part that sets requirements for filing a lawsuit, the PLRA explicitly requires a physical injury to seek monetary compensation. Meanwhile, mental or emotional injury alone is not enough to support a federal civil action without evidence of physical injury.

The distinction between "physical injury versus mental and emotional pain" in the PLRA has limited the large number of lawsuits filed in federal courts over the years. Furthermore, this distinction has been reflected in cases challenging the mental anguish of solitary confinement. In fact, courts have often dismissed mental or emotional harm if there was no proof of physical harm.

In conclusion, the general oversight of mental harm and pain resulting from extreme isolation is closely related to and follows a tendency to discount social interaction as a basic human need. Although the lack of social interaction results in serious mental pain, social interaction is a "mental need," not a physical one. Thus, unlike food and water, it does not qualify as an essential condition for human life.

Finally, by excluding social interaction from the range of human needs that deserve constitutional protection, courts have essentially placed normal confinement and solitary confinement on the same level. Based on several opinions, if the conditions of solitary confinement are largely and materially the same as those of normal confinement, then the Eighth Amendment is not violated. In such cases, neither social interaction nor the mental harm/pain resulting from its deprivation are considered worthy of constitutional protection.

Duration of Extreme Isolation

The limited importance given to mental pain in legal rulings about prison conditions is connected to another critical aspect often overlooked in Eighth Amendment analyses of solitary confinement: how long extreme isolation lasts. As mentioned in the Introduction, solitary confinement practices differ from state to state. Therefore, there is no consistent standard that sets a maximum time a person can spend in extreme isolation. While federal reports and national organizations have issued guidelines recommending maximum time limits for solitary confinement, these limits are largely left to the discretion of prison administrations. This discretion means solitary confinement can be open-ended; it can last for a few days, an indefinite period, or even permanently.

The Supreme Court and lower courts have rarely considered the length of solitary confinement as a separate constitutional issue under the Eighth Amendment. Instead, they have typically viewed the length of solitary confinement as something to evaluate together with (and depending on) the accompanying physical conditions of extreme isolation. Thus, although courts have occasionally recognized that prolonged solitary confinement might be a relevant factor in determining if the Eighth Amendment is violated, this factor has not been treated as an independent part of constitutional review.

Lower federal courts have been more willing to acknowledge the independent importance of duration—and its effects—as an element to assess separately from the physical conditions of solitary confinement. For example, in Sostre v. Rockefeller, the court extensively discussed the issue of duration. The district court tried to set limits on the length of solitary confinement, stating that "to be constitutional, punitive segregation... must be limited to no more than fifteen days and may be imposed only for serious infractions of the rules." Similarly, in O’Brien v. Moriarty, the court observed that, if solitary confinement is "[i]mposed inappropriately, or for too long a period, even the permissible forms of solitary confinement might violate the Eighth Amendment."

Compared to lower courts, the Supreme Court has been more reluctant to recognize the independent constitutional importance of solitary confinement duration. Instead, it has been more willing to link duration to the accompanying physical conditions of solitary confinement. This approach is clear in Hutto. In this case, the Court followed the logic of In re Medley in ruling that solitary confinement alone "is not necessarily unconstitutional, but it may be, depending on the duration of the confinement and (emphasis added) conditions thereof..." Hence, the Court then stated,

"[I]t is perfectly obvious that every decision to remove a particular inmate from general prison population for an indeterminate period could not be characterized as cruel and unusual. If new conditions of confinement are not materially different from those affecting other prisoners, a transfer for the duration of a prisoner’s sentence might be completely unobjectionable and well within the authority of the prison administrator."

As seen from these and other passages, the Court's opinion considers the duration of solitary confinement as part of the question of whether solitary confinement meets constitutional requirements. However, it is only one among many other factors that need to be included in such scrutiny. Thus, the length of solitary confinement is constitutionally problematic only when the accompanying physical conditions of solitary confinement fail to meet constitutional standards.

As observed, one reason that the duration of solitary confinement does not independently fall within the scope of constitutional analysis under the Eighth Amendment stems from the excessive judicial deference to individual prison administrations in deciding and implementing solitary confinement practices. By adopting this hands-off approach, courts have largely left decisions about the length of solitary confinement to prison administrations. As noted, the reasoning for this cites administrations' greater ability to understand and address legitimate prison interests that may require longer periods of isolation.

Despite this long-standing judicial attitude, broader Eighth Amendment concerns regarding long-term solitary confinement have recently re-entered both lower courts and the Supreme Court. Over the past decade, several courts have concluded that the deprivations associated with long-term isolation do violate the Eighth Amendment. For example, in Johnson v. Wetzel, the district court acknowledged the empirical claim that "psychological stressors such as isolation can be as clinically distressing as physical torture." Although the court did not challenge the constitutionality of solitary confinement itself, it found that the psychological deterioration a person suffers as a direct result of prolonged isolation (years in that specific case) is sufficient grounds for an Eighth Amendment violation.

In the same vein, Justice Kennedy's concurring opinion in Davis v. Ayala acknowledged that extended solitary confinement raises serious constitutional questions regardless of its accompanying conditions. As such, the duration of solitary confinement alone should be subject to the Court's constitutional review under the Eighth Amendment. Equally important is Justice Kennedy's criticism of the Court's excessive deference to prison administrations. Prison officials may "have discretion" to use solitary confinement as a "temporary" measure to meet protection or safety needs in prisons; however, this does not prevent courts from assessing, "within [their] proper jurisdiction and authority," the appropriateness of long-term solitary confinement given its widely documented effects on prisoners. Consequently, courts should "determine whether workable alternative systems for long-term confinement exist, and, if so, whether a correctional system should be required to adopt them." Justice Kennedy further argued that the Court's unwillingness to address the excessive length of solitary confinement as a specific matter of constitutional review is essentially an implicit acceptance of the negative effects that a long period of extreme isolation can have on confined individuals. Because the psychological consequences of solitary confinement are widely established and have attracted general attention and concern, failing to address them amounts to an attitude of indifference.

More recently, in Apodaca v. Raemisch and Lowe v. Raemisch, Justice Sotomayor also expressed "deeply troubling concern" over the extreme mental pain caused by long-term isolation itself. Referring to Charles Dickens’ written account of the horrors of solitary confinement in Philadelphia’s Eastern State Penitentiary, Justice Sotomayor emphasized Dickens’ conclusion that, at that time, prison officers were not aware of the "immense amount of torture and agony which [solitary confinement] inflict[ed] upon the sufferers." However, as Justice Sotomayor noted,

"[Today] [w]e are no longer so unaware. [emphasis added] Courts and corrections officials must accordingly remain alert to the clear constitutional problems raised by keeping prisoners like Apodaca, Vigil, and Lowe in 'near-total isolation' from the living world… in what comes perilously close to a penal tomb."

These recent opinions show a clear desire to change how the Eighth Amendment's conditions standard is interpreted. This urge comes from a clear admission of the inhumanity inherent in leaving a person in extreme isolation for an excessively long time. However commendable, this recognition still overlooks the actual constitutional "crux" of solitary confinement, which is extreme isolation. The following sections will specifically address this issue.

The Brain in Solitude

The analysis of how legal decisions about prison conditions relate to solitary confinement suggests that normal confinement and solitary confinement are largely considered the same. This equivalence comes from the fact that both types of confinement can only be challenged under the Eighth Amendment if specific accompanying physical conditions do not meet constitutional standards. Thus, the defining feature of solitary confinement—extreme isolation or social and environmental deprivation—is not enough by itself to be considered an Eighth Amendment violation. In other words, social and environmental deprivation alone is not cruel and unusual punishment. As such, it is entirely constitutional.

Recently, another approach has been taken to challenge solitary confinement under the Eighth Amendment. This approach uses insights from social neuroscience about brain plasticity, social interaction, and environmental stimulation, as well as the effects of social and environmental deprivation on brain function and health. These findings have already been presented in courtrooms in several lawsuits to offer a comprehensive analysis of the impact of solitary confinement, and they provide additional "foundational evidence" of the harms of extreme isolation. The overall message from social neuroscience is that the psychological deterioration following social and environmental deprivation is linked to changes that occur in the brain. These brain changes "have implications beyond the immediately visible behaviors," and can lead to a wide range of negative psychological effects, many of which may be long-lasting or even permanent.

Although neuroscientific evidence has been used on a few occasions, it may offer new support for challenges to solitary confinement under current constitutional standards. In the following discussion, this claim will be explored in more detail. The method involves a brief review of relevant scientific insights and data—many of which have also been introduced in court cases—to highlight three main neuroscience-based challenges to solitary confinement: first, that social interaction is as much a basic physical human need as food or water; second, that social and environmental deprivation causes traumatic changes in the brain, which underlie potentially permanent psychological consequences; third, social pain caused by isolation has a physical basis in the brain, making it ultimately physical.

Necessity of Social Interaction and Environmental Stimulation for Brain Function

In his famous work Politics, Aristotle wrote that "man is by nature a political animal" and "a social instinct is implanted in all men by nature." Therefore, "men, even when they do not require one another’s help, desire to live together." More than two thousand years later, behavioral and neuroscientific fields have provided convincing and consistent evidence confirming that human beings are naturally wired to connect. There is now a general agreement among psychology, anthropology, sociology, and neuroscience that social connection, interaction, and belonging are innate and universal needs for human survival, just as essential as food or water.

In their influential and widely cited work, Baumeister and Leary suggested that people are driven by an innate need to belong, which programs them to form and maintain relationships. This need to belong is therefore an inborn and universal motivation for human behavior. The authors defined this need as the desire to form and maintain strong, stable interpersonal relationships. They importantly argued that this need is met through frequent human contact and genuine caring bonds between individuals.

Baumeister and Leary proposed nine criteria to determine if a human need is a fundamental motivator for behavior. Specifically, the need should:

(a) produce effects easily under most conditions, (b) have emotional consequences, (c) guide how people think, (d) lead to negative effects (like on health or well-being) when blocked, (e) cause goal-oriented behavior to satisfy it (with flexibility like substituting one object for another and reaching satisfaction), (f) apply to all people universally, (g) not be a result of other motivations, (h) influence a wide range of behaviors, and (i) have implications beyond immediate psychological functioning.

The authors then reviewed a large body of evidence showing that belonging and social connection meet all of these criteria. Based on this, they concluded that the need to belong is indeed a fundamental human need.

Different scientific research perspectives support Baumeister and Leary's conclusion. For example, several studies have suggested that social interaction influences the development and expression of executive functions. Additionally, social engagement and participation in meaningful social activities have reportedly helped people maintain their thinking skills better and delay cognitive decline in middle and older adulthood. Epidemiological studies have linked social connection and meaningful interactions to better physical and mental health, as well as lower rates of illness and death. Other studies have also indicated that consistent meaningful social connections and bonds help individuals develop and maintain socio-emotional skills, such as empathy and emotion regulation, which are important factors influencing prosocial attitudes and behavior. Importantly, these insights align with findings from studies on crime desistance.

Brain function helps explain why social connection and interaction are so vital for human beings. Following Dunbar’s "social brain hypothesis," Matthew Lieberman proposed that the brain size of different species, specifically the size of their neocortex, corresponds to the size of their social environments. According to this hypothesis, humans have large brains—and the largest neocortex of all species—to meet their complex needs for socialization. Specifically, the human brain is organized to perform social thinking in order to navigate complex social interactions and environmental surroundings.

In a similar vein, Daniel Siegel has suggested that the brain is "a social organ." On one hand, the brain triggers our mental processes and bodily experiences when exposed to social stimuli, thereby guiding our behavioral responses toward others and contributing to our social skills and relationships. Essentially, the brain is the organ that enables social interactions, as it maintains our connections with other individuals. On the other hand, physiological and neurological reactions are directly and profoundly shaped by social interactions. Such interactions, which range from face-to-face conversations to feeling another person's touch, act as modulators, comparable to interpersonal "thermostats" that continuously shape our brain function.

Consistent with these insights, important research on brain plasticity has shown that positive social engagement leads to positive changes in the neural circuits that support cognitive functions, socio-emotional skills (e.g., empathy), and social behavior throughout a person's life. These changes have been linked to higher cognitive performance, psychological well-being, and prosocial behavior.

Studies on social interaction and brain plasticity connect with those on the continuous influence of environmental stimulation on the brain. These studies have mostly used animal models. For example, studies with rodents have shown that rodents raised in "enriched environments" and surrounded by their peers exhibited normal developmental pathways in the structure and function of several brain areas. These areas support various functions, from typical cognitive abilities to emotion-related functions like learning, memory, and emotion regulation. Importantly, these animal samples also showed normal social tendencies.

Several studies have suggested that some of these physical and functional characteristics can be explained by neurogenesis, which is the growth of new cells in brain regions. Evidence implies that enriched environments "enhance cell proliferation and neurogenesis in the brain, notably in the regions critical for social interaction, memory, and communication," including the hippocampus. As will be discussed shortly, social and environmental deprivation appears to hinder neurogenesis in these same brain regions and lead to negative psychological and behavioral consequences.

In summary, there is a fundamental two-way relationship between the brain and the social environment. On one hand, the complex organization of the human brain allows humans to fulfill their biological need to connect and interact with their social world. On the other hand, the social world enables, nourishes, and shapes the brain mechanisms that support the cognitive, emotional, and socially relevant abilities that allow humans to function individually and socially. Thus, social connection or interaction in stimulating environments is crucial for protecting brain function and health. According to Lieberman, "no one will die from lack of social contact over a few days, but people will show evidence of being in a deprived state within a short period and a lack of social connection will likely produce a wide array of negative outcomes for an individual’s mental and physical well-being before long." Therefore, when social and environmental connection is missing, the brain—and the person as a result—will likely experience profound traumatic consequences in the long term.

The Neurobiological Effects of Social and Environmental Deprivation

A vast amount of clinical and experimental research has documented the effects of solitary confinement on both healthy and unhealthy incarcerated populations. This research consistently reaches the same dramatic conclusion: solitary confinement can cause potentially permanent cognitive, emotional, and physical damage.

For example, in his clinical observational studies, Stuart Grassian reported three main "typical features" of the general psychological effects of solitary confinement: (1) distorted perceptions, illusions, and hallucinations in various areas; (2) emotional disturbances including anxiety and panic attacks; and (3) obsessive, intrusive thoughts sometimes accompanied by compulsive behavior. According to Grassian, most affected individuals may even develop psychotic disturbances with a dissociative character; while those less affected still experience significant psychiatric harm including intense anxiety, obsessive thinking, agitation, paranoia, and irritability.

Grassian’s findings support those from other psychological studies that have linked life in solitary confinement to a wide range of negative psychological effects including rage, irrational anger, fears of persecution, lack of impulse control, severe and chronic depression, loss of appetite, heart palpitations, withdrawal, and apathy—to name just a few. This body of literature has also documented the dehumanizing effects of social isolation, which include, but are not limited to, a lack or loss of a sense of belonging, self-esteem, meaning, and self-identity. The dehumanizing effects of social isolation have been linked to a higher risk of engaging in harmful, antisocial, and destructive behavior.

Notably, research suggests that the psychological impairments caused by solitary confinement continue even after an individual is released from prison and returns to a social environment. Specifically, people released back into the community after serving time in solitary confinement are "incapable of accommodating to life" due to an oversensitivity to sensory stimulations. This leads to an intolerance to typical daily noises, like the chaos of a restaurant, and social stimulations, including an inability to participate in family moments, such as eating meals together.

Scientific research has begun to identify the brain changes that appear to be linked to the psychological effects of social and environmental deprivation (or extreme isolation). For example, electroencephalography (EEG) studies have shown that a few days in solitary confinement can cause brain injury-like wave alterations. These alterations have been connected to an oversensitivity to external stimuli, inadequate attention and alertness to the environment, as well as "a complete breakdown or disintegration of the identity of the isolated individual."

Clinical and experimental studies that have documented the effects of solitary confinement on the brain are supported by a strong body of experimental animal research. This research helps us understand the various brain mechanisms that underlie the psychological and psychiatric symptoms observed in incarcerated individuals who have been isolated for long periods. These studies have collectively revealed that social and environmental deprivation negatively affects both brain structure and function, including reduced cortical volume, fewer neuronal connections in cortical areas and the hippocampus, decreased myelin production, and altered activity in the reward system and the amygdala. These brain changes have been linked to detachment from the environment, hostility towards others, high levels of aggression, as well as an increased risk of susceptibility to several behavioral conditions that mimic psychiatric diseases and disorders in humans, including neurodegenerative disorders and schizophrenia. Importantly, physical and functional changes in the brain can occur even after a short period of time and appear to continue after the subject is reintroduced into the social environment.

A significant body of research has examined the neurobiological effects of chronic stress caused by social and environmental deprivation. For instance, studies with rodents have shown that rodents housed alone, unlike those housed in enriched environments, develop a smaller cerebral cortex and shorter synapses in brain areas involved in spatial information processing, memory, social information, and emotion regulation, including the hippocampus. Additionally, some studies have linked physical and functional reductions in the hippocampus to decreased hippocampal neurogenesis (the growth of new brain cells). These damages have been associated with long-term mental health conditions in humans, such as memory loss, cognitive decline, depression, and post-traumatic stress disorder.

Other than the hippocampus, another limbic region that appears to be affected by social and environmental deprivation is the amygdala, which mediates emotional arousal in response to perceived stimuli. The amygdala is also involved in experiencing and processing fear and anxiety. Studies with rodents have indicated that high stress increases cortisol levels, which in turn alter neuron proliferation in the amygdala and produce negative psychological and behavioral effects like anxiety, deficits in social interaction, and poor regulation of social behavior.

At the cortical level, studies with isolated rodents in poor environments observed reduced levels of myelination in the prefrontal cortex. Impaired myelination in this brain area has been reported for a number of psychiatric illnesses, including anxiety, autism, schizophrenia, and depression. Other studies with rats have shown that isolation-reared rats exhibited reduced medial prefrontal cortex (mPFC) volume compared with group-reared rats. Among humans, reduced mPFC volume has been associated with several core symptoms of schizophrenia, such as fear of new things, impaired memory, and problems with sensory processing.

Studies on social isolation relate to and complement research on loneliness, which is the personal feeling of isolation. While loneliness is not always or necessarily linked to physical and objective isolation, such isolation can contribute to feelings of loneliness. Behavioral research on loneliness has identified perceived social isolation as a risk factor for "poorer overall cognitive performance, faster cognitive decline, poorer executive functioning, more negativity and depressive cognition, heightened sensitivity to social threats" as well as "an increased implicit vigilance for social threats along with increased anxiety, hostility, and social withdrawal;… decreased impulse control in favor of responses highest in the response hierarchy (i.e., prepotent responding); increased negativity and depressive symptomatology…." Furthermore, several studies have highlighted connections between the symptoms of loneliness and the neurobiological changes that occur following objective social isolation.

Overall, there is strong evidence for the harmful and long-lasting neurobiological effects of social isolation and environmental deprivation. This evidence suggests that many of these effects are difficult to reverse, even when the individual returns to a social environment. It is true that many questions about the exact implications of social and environmental deprivation for the human brain and behavior remain unanswered. These include how long a person can be isolated without risking irreversible damage, or how factors like age, gender, or personal background affect the severity of social and environmental isolation for the brain and behavior. As noted, many of these questions are difficult to study in human subjects.

While answering these questions is crucial for fully understanding the precise effects of solitary confinement on the brain and behavior, current evidence is reliable and consistent enough to suggest that "increased social isolation and diminished physical contact contribute to and reinforce problematic neurobiological patterns." Therefore, the deprived conditions of solitary confinement will most likely "generate or exacerbate neurobiological deficits and maladaptive behaviors... [t]his becomes a significant issue, especially for individuals who are chronic offenders, where existing neurobiological vulnerabilities are intensified in settings of confinement and segregation, thereby reinforcing maladaptive patterns of behavior." In sum, neuroscience research indicates that the essential features of solitary confinement, namely social and environmental deprivation, can alone cause significant brain damage, all of which risks leading to long-lasting or even permanent traumatic psychological and physiological consequences. So far, these consequences have mostly been overlooked in courtrooms.

Social Pain Is Physical

A key insight from social neuroscience regarding how social and environmental deprivation affects the brain concerns social pain. As noted, common ideas about pain and the law itself are based on the assumption that physical pain and social (mental) pain are different in their characteristics and nature. Physical pain is generally understood as pain from a bodily injury or the lack of a physical need; as such, it is objective, measurable, and tangible. Meanwhile, social pain is seen as purely mental, subjective, and almost "non-existent." Therefore, it is largely ignored as an internal experience with no tangible effects. As discussed, this division of pain is widespread in law and also appears in legal rulings about solitary confinement. To challenge these common beliefs, a growing body of research in social neuroscience suggests that social pain is deeply embedded in the brain. As such, social pain is fundamentally physical.

The most influential theory regarding adverse social experiences, known as the shared representation theory, suggests that physical pain and social pain "rely on shared neural circuitry." According to this view, the experience of social pain stems from the natural and universal human need for social connection and belonging. From an evolutionary standpoint, this natural need likely originated from the long period during which mammalian infants critically depended on maternal attachment, care, and nurturing to survive. The absence of these fundamental needs creates a feeling of rejection, which the individual perceives as painful and distressing. Based on this survival need, it is possible that "the social attachment system—which ensures social connection—may have piggybacked directly onto the physical pain system, borrowing the pain signal itself to indicate when social relationships are threatened." Thus, the experience of social pain can be understood as an adaptive way to prevent and survive the threat of social rejection and exclusion. As Lieberman and Eisenberger put it, "[j]ust as evolution has wired us to feel pain when we lack food (e.g., hunger), water (e.g., thirst), or shelter (e.g., freezing, sunburn), perhaps evolution has wired us to feel pain when we lack… social connection."

Building on this perspective, neuroimaging research by Lieberman and Eisenberger has reported significant overlap between physical pain and social pain in the brain. Specifically, their studies indicated that the experience of physical pain involves two distinct parts: a sensory component, supported by the primary and secondary somatosensory cortex and the posterior insula; and an emotional component, which is the distressing experience of pain, supported by the dorsal anterior cingulate cortex (dACC) and the anterior insula (AI). Neuroimaging studies from this research line have suggested that the experience of social pain activates neural pathways typically involved in the emotional component of physical pain processing—i.e., the dACC and the AI. These studies also showed that people who are more sensitive to physical pain will also be more vulnerable to experiencing social pain. Interventions aimed at relieving physical pain also appear to be effective in relieving social pain.

Social pain has been linked to both physical and objective isolation (meaning an actual lack of social connection) as well as perceived isolation (meaning loneliness). Several laboratory studies within the reported research have explored the connection between experiencing social pain and social disconnection (caused by social isolation) through neural activity in the brain regions that support this form of pain. These findings likely explain why individuals with higher levels of objective or subjective isolation are at a greater risk of developing physical and mental health problems, and even a higher risk of mortality. As Eisenberger has explained, "given that the dACC and AI are involved in responding to social disconnection, these regions may have a role in translating experiences of social disconnection into downstream physiological responses—such as heightened inflammatory activity, the immune system’s first line of defense against foreign agents and infection…." Increased inflammatory activity has been found to relate to negative physical and mental health outcomes, including heart diseases and depression.

Finally, this series of functional magnetic resonance (fMRI) studies has also begun to investigate how social pain affects aggression through activity in the dACC and AI. Preliminary results show a positive correlation between increased activity in these two brain regions (linked to the experience of social pain) and increased levels of aggression in socially rejected individuals who have less executive functioning (regulatory capability). These results suggest that social pain contributes to aggressive reactions among socially rejected individuals.

In partial contrast to Eisenberger and Lieberman's work, another fMRI study, led by Tor Wager, used a more detailed analysis and found distinct neural representations of physical pain and social pain within core pain-processing brain regions and across other brain regions. Notably, this work indicates that physical pain and social pain involve independent neural representations despite similar fMRI activity at a broad anatomical level (e.g., in the dACC and AI). Thus, rather than using the same circuitry as physical pain, social pain appears to involve different emotional representations in the brain. Based on these findings, these researchers have proposed that physical pain and social pain are ultimately distinct types of emotion that may lead to unique consequences at the psychological level; therefore, they require different types of interventions. Still, the authors highlighted that physical pain and social pain may still be functionally related and influence each other. For example, evidence indicates that individuals who suffered emotional trauma are at a higher risk of developing pain disorders.

Despite the scientific disagreement over whether social pain is neurologically similar to physical pain, neuroscientific findings on the nature of social pain collectively provide two critical insights for this article. First, the lack of social connection—i.e., social isolation—leads to a range of negative emotional states, adverse psychological effects, and harmful behavioral patterns that are linked to the pain of being socially excluded or rejected. Second, this social pain has a physical reality in the brain. As such, it should be considered "real pain," rather than a "metaphorical pain." Importantly, the experience of social pain is not less serious or less harmful than that of physical pain. Rather, its consequences for an individual may well be more distressing and damaging than those following forms of physical pain. Thus, continuing to rank physical pain over social pain is problematic. Most importantly, it severely overlooks the kind of suffering that social pain due to isolation can cause, which can be equally intense and equally (or even more) traumatic and long-lasting compared with the physical pain one might experience from lacking a tangible, physical need.

Solitary Confinement is Per Se Cruel and Unusual Punishment

The body of neuroscientific research on the critical importance of social interaction for brain structure and function, combined with insights into the damaging effects of social isolation and environmental deprivation on the brain, mind, and behavior, could re-energize challenges to solitary confinement.

While more precise scientific answers are needed to fully understand the variety and extent of solitary confinement's implications for the brain and behavior, existing evidence can provide additional empirical support to challenge the core of solitary confinement: extreme isolation. As noted, insights into the traumatic consequences of extreme isolation from the neurosciences align with those from various international bodies who have stressed that "all forms of solitary confinement without appropriate mental or physical stimulation are likely, in the long term, to have damaging effects."

Based on these insights, the remainder of this article presents three main points supporting the argument that solitary confinement, as currently practiced in many jurisdictions, inherently violates the Eighth Amendment's ban on cruel and unusual punishments. First, the core feature of solitary confinement—extreme isolation or social and environmental deprivation—fails to meet the current conditions standard. Second, there is a clear imbalance between the widespread traumatic and potentially permanent implications of social and environmental deprivation and the prison's legitimate goals of discipline, security, and safety that solitary confinement is intended to serve. Furthermore, and more broadly, solitary confinement goes against all reasons for punishment. Acknowledging that solitary confinement fails to meet any relevant Eighth Amendment requirement means that solitary confinement is inherently unconstitutional.

Failure to Meet Current Conditions Standard

The body of neuroscientific research on the effects of social and environmental deprivation on the brain provides a strong scientific basis for the argument that social and environmental deprivation (or extreme isolation)—the core of solitary confinement—qualifies as an Eighth Amendment violation under all parts of the current conditions standard. This section discusses each part in turn.

Social Interaction and Environmental Stimulation as Basic Human Needs

Consistent with evolutionary perspectives, neuroscientific research has provided a compelling argument for classifying social interaction as a basic human survival need, on par with other identifiable physical needs such as water, food, or shelter. As discussed, social interaction is simply inherent to the nature of humans, who are fundamentally social beings. This inherent quality arises from the mutual and inseparable relationship between the brain and the social environment. Furthermore, the neurobiological need for social interaction includes and is complemented by the need for environmental stimulation. As discussed, environmental stimulation significantly contributes to brain development and behavior, and the human brain must constantly receive a variety of sensory inputs from the external environment to function properly. Overall, the evidence discussed above indicates that social interaction and environmental stimulation are essential conditions for physiological brain function. As such, depriving human beings of social contact and environmental stimulation is equivalent to depriving them of their very nature.

Acknowledging the vital importance of social interaction in stimulating environments means that forcing individuals into isolation in tiny, environmentally poor cells is enough by itself to deprive them of basic human needs. Therefore, individual physical conditions of solitary confinement (e.g., lack of heating, proper bedding, or winter clothing) should be seen as circumstances that worsen and are secondary to an underlying condition—extreme isolation—which alone is enough to constitute a serious deprivation of basic human needs.

Importantly, including social interaction and environmental stimulation in the range of basic human needs also challenges the courts' view that normal confinement and solitary confinement are largely the same. As reported, courts have supported the idea that solitary confinement is legitimate as long as its conditions, such as providing nutrition and shelter, are not significantly different from those affecting the general prison population. Thus, solitary confinement is not cruel and unusual as long as it guarantees the same basic human needs that are ensured to the general prison population. However, this equivalence fails to consider that extreme isolation is the condition that makes the two types of confinement fundamentally different. This difference comes precisely from the fact that solitary confinement deprives individuals of a survival need that normal confinement guarantees. Considering this fundamental distinguishing aspect and its consequences, normal and solitary confinement cannot be placed on the same level. Instead, the evaluation of solitary confinement should be based on its own criteria, which should systematically recognize social interaction as a fundamental need rather than a mere privilege.

Social-Environmental Deprivation (Extreme Isolation) Entails an Objectively Serious Risk of Physical Harm

If the vital role of social interaction and environmental stimulation for the human brain and behavior is not enough to establish them as basic physical needs, then evidence of the risks that social and environmental deprivation poses to the brain adds significant weight and encourages a reconsideration of the "substantial risk of serious harm" requirement in relation to solitary confinement.

As discussed, the brain changes or deteriorations that follow social and environmental deprivation appear to underlie a number of negative cognitive, emotional, and behavioral patterns, and they have also been reported in major psychiatric disorders, including depression and schizophrenia. These findings support and corroborate the existing robust body of psychological studies that have documented the dramatic psychological and psychiatric effects of solitary confinement. Moreover, brain and psychological damage due to social and environmental deprivation has been found to contribute to physical health problems and even increase the risk of mortality. From this perspective, the disfiguring damage that solitary confinement could inflict on prisoners can be long-lasting or even permanent.

Equally important are insights into the nature and implications of the social pain caused by social isolation. Besides indicating that social pain has physical reality, neuroscientific research has crucially suggested that the experience of social pain can be far worse than that of physical pain in many respects. Social pain has been linked to a series of psychological symptoms, including humiliation, low self-esteem, harmful actions, including aggression, and lower levels of physical and mental health, especially in the long term. Thus, even if the traumatic effects of social pain are not immediately visible, they may manifest and grow over time.

By translating neuroscientific insights into the language of legal rulings on prison conditions, one can make the following observations. First, social and environmental deprivation does involve an objectively serious risk of physical harm that is comparable to that of food or sleep deprivation. Even if the harm that solitary confinement inflicts on the brain translates into mental deterioration, and is therefore mental, it is also undeniable that "the type of severe psychological deterioration observed in solitary confinement is due to physical harms imposed on the brain." As such, it is ultimately physical.

Second, the harm that solitary confinement imposes on the brain underlies a number of long-lasting or potentially permanent mental, physical, and physiological conditions. Therefore, the possible harms of solitary confinement are not only disfiguring but also potentially permanent. Last, and perhaps most importantly, the risk of such physical harms may appear even after a short period of extreme isolation. As mentioned, (neuro)science has not yet determined with enough precision how long an individual can spend in isolation without suffering irreversible brain damage. However, there is a consensus across scientific fields (including neuroscience) that the amount of time an individual spends in socially and environmentally deprived conditions directly relates to the degree of risk that they will suffer neurological, physiological, psychological, and physical deterioration.

It is true that not everyone will necessarily and inevitably suffer irreversible damage, and not everyone will experience the same kinds of trauma after the same amount of time. However, as Bennion correctly noted, "the fact that serious risks may never materialize in serious harm (or that harm may not be imminent) is not conclusive for... the test." Furthermore, the risk of undergoing serious brain and mental deterioration following solitary confinement is universal: any person is vulnerable to such risk, regardless of their history of mental illness.

Given the insights above, solitary confinement alone also meets the "substantial risk of serious (physical) harm" requirement of the objective part of the conditions standard. By denying individuals a minimal life necessity, solitary confinement itself risks inflicting unnecessary suffering characterized by disfiguring and potentially permanent consequences. As the Court has repeatedly stated, the interpretation of the Eighth Amendment changes in line with the knowledge and standards of decency of an evolving society. A punishment that risks inflicting disfiguring and potentially permanent damages on individuals exceeds contemporary standards of decency, and no civilized society should tolerate such a toll on human beings.

Deliberate Indifference Follows From Extreme Isolation

As noted above, the subjective part of the conditions standard has been criticized by scholars, especially in solitary confinement cases. It can be extremely difficult to prove that prison staff or administrators were deliberately indifferent to the harm inflicted on prisoners by a serious denial of basic human needs. Such challenging proof can hinder the success of legitimate Eighth Amendment claims based on harmful solitary confinement conditions.

Courts have acknowledged that when the risk of serious harm from a confinement condition is objective and widely known, such objective proof is also sufficient to infer the culpable state of mind of prison personnel. Regarding solitary confinement, several court opinions have questioned the necessity of explicit proof of deliberate indifference, given that placing prisoners in solitary confinement poses a substantial risk of serious harm. For instance, the court in Wilkerson noted that "basic common sense indicates that 'lack of exercise, social isolation, and/or stress are associated with [deleterious] conditions'.... [Therefore, a] court 'may infer the existence of this subjective state of mind [i.e., deliberate indifference] from the fact that the risk of harm is obvious'." Similarly, opinions in Supreme Court cases have stressed the growing awareness of the damages of solitary confinement in modern American prison systems. Such damages have been thoroughly documented and acknowledged by scientific, legal, and and international sources.

Furthermore, several authors have supported a presumption of culpability for prison officials in cases seeking injunctions. For example, it has been suggested that "prisoners could certainly show by the time of trial that authorities were aware of either the actual harm or risk of harm caused by solitary confinement." Thus, when harmful conditions are allowed to continue, courts may infer the culpable mindset of prison officials from the conditions themselves without also requiring explicit proof of that mindset.

This article's argument further strengthens these claims. When acknowledging that the core condition of solitary confinement, namely extreme isolation, itself amounts to an unnecessary and wanton infliction of pain and constitutes cruel and unusual punishment, the subjective part of the test loses its purpose and becomes unnecessary. Given the growing general awareness of the objective damages linked with solitary confinement, proof of social and environmental deprivation is sufficient to infer that prison officials acted with deliberate indifference, as extremely isolating a prisoner is essentially depriving them of a basic human need and involves an objectively serious and well-known risk of harm. Therefore, a fact-finder could conclude that by keeping a prisoner in solitary confinement despite the obvious health risks, both physical and psychological, the prison staff acted with deliberate indifference to the substantial risk of consequent harm.

Failure to Meet the Intended Penological Aims

The evidence of the widespread consequences of solitary confinement also disrupts the supposed balance between the "pains" of solitary confinement and the legitimate prison interests of discipline, security, and safety. This "newly" emerging imbalance comes from the fact that social and environmental deprivation, especially when prolonged, risks causing severe brain damage, even in individuals without a history of mental illness. Such damage may not be limited to the period of isolation; given the long-lasting psychological consequences they entail, the effects of such damage risk continuing even after an individual is reintroduced into a social environment, whether it is the prison or the general community. The risk of undergoing brain damage due to extreme isolation is an excessive—and, therefore, extremely unbalanced—cost for any legitimate prison interest to supposedly justify it.

These claims reinforce the strong body of evidence showing that neither short-term nor long-term stays in solitary confinement achieve specific deterrent effects by reducing future disciplinary infractions or prison incidents. Instead, evidence shows that stays in solitary confinement appear to produce the opposite effect. Moreover, jurisdictions that have limited the use of solitary confinement have seen a decrease in prison violence. Thus, limiting the use of solitary confinement does not undermine prison administrators' ability to control the prison population or maintain safety and may actually increase it.

Acknowledging these claims may prompt courts to reconsider their (often excessive) deference to prison administrations regarding the management and application of solitary confinement practices. Specifically, it may encourage courts to carefully scrutinize the "legitimate penological justifications" that prison administrations cite to defend their use of solitary confinement. This could fully realize the constitutional protection of people in custody that lies at the heart of the Eighth Amendment.

From a broader perspective, evaluating the legitimate justifications for a prison condition or correctional practice under the Eighth Amendment must consider how knowledge progresses, reflecting society's evolving standards of decency. Currently, there is a general consensus among domestic and international bodies that disfavors solitary confinement, suggesting that standards of decency have moved away from using solitary confinement to serve its intended purposes. Increased knowledge also reflects (the reasons for) the greater effectiveness of less restrictive and less painful methods to serve identical purposes. Thus, no legitimate prison interest can justify the systematic and indiscriminate use of solitary confinement. Moreover, no prison interest can outweigh the damage that solitary confinement risks imposing on incarcerated people. It is true that solitary confinement may still be justified in instances requiring an individual's temporary protection or for the most serious, violent offenses or rule violations, but only when other measures have been tried without satisfactory results. Even in such instances, separating an individual from the rest of the prison community can still be handled in a more humane and less restrictive way.

The Antithesis Between Solitary Confinement and the Goals of Punishment

Solitary confinement and its effects are also inconsistent with the goals of punishment: retribution, incapacitation, deterrence, and rehabilitation. As such, it lacks any real purpose in corrections. Although this broader correctional perspective is not common in Eighth Amendment analyses in cases involving confinement, explaining why solitary confinement goes against each main reason for punishment can still offer academic value.

Starting with retribution, analyses based on retribution generally include two parts. The first, which is objective, evaluates a punishment based on the seriousness of the crime committed. The second, which is subjective, evaluates a punishment considering the degree of blame of the person who committed the crime. Evaluations of blame also include the individual characteristics of the person, such as their age or mental abilities. Therefore, from a retributive perspective, a punishment is disproportionate if it is excessively severe compared to the crime and the offender's overall degree of blame and, consequently, fault.

For the purpose of this article, solitary confinement is measured against another critical aspect of retributive theory: preserving and respecting the moral rationality of offenders. The idea of moral rationality is undeniably central to any retributive punishment. Retribution assumes that the offender is a rational moral agent capable of understanding the meaning and consequences of their actions and freely chooses to act unlawfully. Based on this assumption, retributive punishment aims to ensure that offenders are "capable of understanding the wrongs they have committed and the fairness of the penal sanctions imposed on them by the state in response to those wrongs." Accordingly, retributivism insists on structuring legal punishment to be, at minimum, consistent with treating offenders as rational moral beings.

Retributivism requires that imprisonment deprives offenders of their freedoms by significantly reducing their privileges to live autonomous lives. However, retribution does not require that imprisonment also erodes the capacities that define moral personhood, such as "physical and psychological health, work, and interaction with others." From a retributive perspective, these capacities and dispositions need to be regularly exercised to maintain prisoners' ability "to comprehend and respond constructively to the reasons for which they are being punished."

From this line of reasoning, solitary confinement does not align with this fundamental aspect of retributive punishment. Solitary confinement risks inflicting traumatic brain and mental damage on prisoners, all of which compromise the cognitive and emotional abilities that support practical reasoning skills, and "cause further atrophy of what may have already been weak capacities to identify with and feel for others." Furthermore, the long-lasting or even permanent physiological, mental, and physical damage that solitary confinement can cause may continue even after a prisoner has completed their sentence. Therefore, solitary confinement, which can inflict long-lasting or even permanent losses on offenders, makes a prison sentence disproportionate to the seriousness of the crimes committed. Such an outcome is simply contrary to any mainstream retributive perspective.

Solitary confinement also fails to meet the consequentialist goals of punishment: incapacitation, deterrence, and rehabilitation. Incapacitation refers to how punishment, especially imprisonment, reduces the likelihood that offenders will commit further crimes by physically removing them from society. Solitary confinement, especially in supermax facilities, serves this purpose during the period of confinement. However, the benefit of this incapacitation argument for public safety requires further analysis of the specific deterrent effects of solitary confinement.

Theories regarding the use of solitary confinement emphasize its potential to prevent future crime. However, scientific evidence contradicts the effectiveness of solitary confinement as a tool to reduce repeat offenses or change prisoners' behavior. There is evidence that prisoners in solitary confinement in supermax prisons fare even worse than prisoners in the general population once they are released. For instance, an epidemiological study by Maers and Bales compared the rates of repeat offenses among individuals who had been in solitary confinement with those of individuals who had been in normal confinement. They found that solitary confinement was associated with a higher risk that formerly incarcerated individuals would commit a violent crime after being released. Other epidemiological studies have replicated this finding. The reasons for the increased risk of repeat offenses largely stem from the brain changes due to solitary confinement, which have been linked to negative psychological symptoms and mental health issues known to be risk factors for socially dysfunctional behaviors, including antisocial conduct.

Last but not least, solitary confinement does not serve the rehabilitative ideal of punishment. (Social) rehabilitation clearly aims to reintegrate convicted individuals into society upon their release so that they can lead law-abiding and self-supporting lives. Thus, it seeks to re-establish positive relationships between offenders and the rest of society by facilitating (self-)reform and change based on relational processes. Rehabilitation crucially promotes as much inclusiveness and positive social engagement as possible while offenders serve their sentence, as this can facilitate their social reintegration into the community.

In addition to opposing the core values and aims of rehabilitation theory, the potential harms of solitary confinement, including a greater tendency towards aggression and other harmful psychological and behavioral patterns, can seriously compromise an individual's social functioning. Therefore, these harms severely hinder the rehabilitation and re-socialization process, making it more difficult, if not nearly impossible in some cases.

To conclude, the type and extent of harm that solitary confinement can inflict on individuals do not align with and are therefore disproportionate to any correctional justification. Given this, solitary confinement constitutes an unnecessary and wanton infliction of pain because it not only deprives individuals of their basic social and environmental biological needs but also lacks any kind of correctional justification. The suffering that solitary confinement imposes is unnecessary and violates any relevant perspective under the Eighth Amendment. No correctional interest or goal can justify its infliction; solitary confinement is inherently cruel and unusual punishment.

A Path Forward: Abolishing Solitude in Prison

The arguments presented in this article ultimately support the conclusion that solitary confinement, as it is still administered in many facilities or prison systems, should be eliminated entirely. This conclusion aligns with the wide range of domestic and international organizations, movements, and associations that have called for abolishing solitary confinement or at least limiting its use to exceptional and strictly regulated circumstances.

Separating a prisoner from the rest of the prison population should always be a last resort, used only in extreme cases—which must be properly documented by prison staff and potentially overseen by specialized committees—and only when absolutely necessary to achieve legitimate prison goals. In such cases, the separation of an individual from the rest of the prison community should be subject to strict time, social, and environmental standards. These (possibly uniform) standards are needed to counter arbitrary forms of solitary confinement and a constitutional weakness that allows prison administrations to use solitary confinement with little judicial oversight.

Regarding time limits, the ASCA-Liman survey reported time intervals ranging from between 1 to 15 days to more than six years across jurisdictions. Although fewer people were kept in solitary for 1-15 days, higher percentages were reported for periods in solitary of at least one month to over six years.

More empirical research is needed to determine the exact maximum time limit for depriving an individual of constant social contact without causing irreversible damage; however, acknowledging that such deprivation risks causing or worsening physical, physiological, and psychological adverse effects even after just a few days provides sufficient grounds for adopting uniform maximum time limits that align with existing scientific knowledge and domestic and international guidelines. Given the current lack of legal precedent on duration limits for solitary confinement, the strength of international and domestic guidelines mandating a maximum of 15 days of solitary confinement should be used as a benchmark to set uniform time standards in all jurisdictions. All states should adhere to these standards, with any violation constituting an Eighth Amendment violation.

In addition to setting uniform time limits on solitary confinement, uniform sociability standards are also warranted. The ASCA-Liman survey also reported positive data from several jurisdictions that have implemented specific policies in recent years to restrict the use of solitary confinement to the most objectively serious cases in order to improve the "social" conditions of people housed in solitary cells. Several jurisdictions have put in place policies that allow more time out of the cell, outdoor recreation activities, classes, job training, rehabilitation, and re-entry programs for restricted individuals. However, only a few of them have increased visiting hours. Some policies even offer training for correctional officers to learn alternative responses to prison violence that focus on dialogue, accountability, and cooperation. Notably, statistics show that both prison incidents and the overall rate of repeat offenses upon re-entry to the community have decreased. These scattered changes are encouraging and show a growing recognition that solitary confinement is counterproductive and can be extremely damaging. Ensuring that all correctional facilities adopt and apply sociability standards—including recreation, education, rehabilitation programs, and visiting hours with significant others—for prisoners temporarily separated from the rest of the community is crucial to counteract the negative effects of isolation and aid in their social rehabilitation and re-entry process.

Finally, although this suggestion applies to correctional facilities in general, the design of separation cells should follow strict environmental standards. On several occasions, the Court stressed that "the Constitution does not mandate comfortable prisons." However, it also stated that the Constitution "neither does... permit inhumane ones." The empirical studies reported above indicate that environmental surroundings—whether stimulating or deprived—significantly influence brain structure and function, as well as psychological well-being and social behavior. Tiny and environmentally poor cells risk worsening the negative effects of a lack of social interaction.

Several authors have called for making correctional facilities as humanized and home-like as possible. Positive international examples show that home-like cells with natural light, even in maximum security facilities, where prisoners are provided amenities such as proper bedding, furniture, or reading materials, contribute to prisoners’ physical and psychosocial well-being. Such overall well-being has been found to positively contribute to reduced institutional misconduct and overall repeat offending.

It is admittedly difficult to expect such a dramatic change in U.S. facilities in the immediate future. Nevertheless, it is crucial to acknowledge that such realities exist and are effective. Most importantly, those realities convey an important lesson of "dignity and humanity that is the birthright of every person, and... respect [for] the collective dignity and humanity of society." These are the values and rights that animate the Eighth Amendment, and should accordingly animate the abolition of solitary confinement.

Conclusion

In the opening paragraph of her dissenting opinion in Apodaca, Justice Sotomayor wrote, "A punishment need not leave physical scars to be cruel and unusual." However, social and environmental deprivation can apparently leave many scars, which may be visible and tangible. Solitary confinement is a disfiguring and dehumanizing punishment, as it deprives people of their biological needs, drastically changes their physiology, and causes severe psychological and physical harm. It is increasingly an appropriate time to address the many, potentially incurable scars that solitary confinement can inflict on incarcerated people. Continuing to ignore these scars can only make them even more profound.

Summary

Solitary confinement in the U.S. is a known issue. People in prison are often held alone for long periods without much contact, sometimes in bad living conditions. While this happens in many prisons, solitary confinement is meant to help with discipline, safety, and security.

The rules for solitary confinement are not the same everywhere. Each state's prison decides how to use it. Because of this, there have been problems and calls to stop or greatly change solitary confinement in the U.S. Some changes have been made to limit how long people can be in isolation or to keep people with mental health issues or young people out of it.

But progress has been slow. A report showed that while some states use solitary confinement less, others use it more.

Courts have also looked at solitary confinement to see if it causes "cruel and unusual punishment." This means conditions that cause "needless pain" or take away "basic human needs," causing harm or a "big risk of serious harm." But courts have not often seen the mental pain of being alone as serious enough.

However, new science is showing that being alone for a long time can hurt the brain. This research suggests that being with others is very important for brain health. Studies show that being alone for even a short time can cause brain damage and lead to lasting mental problems, including anger. This new information can help argue that solitary confinement is always cruel and unusual punishment.

Solitary Confinement in Court Decisions

The meaning of "cruel and unusual punishments" in court cases has not been fully decided. But over the years, the Supreme Court has looked at it in two ways.

First, for punishments given by courts, they check if the punishment fits the crime. A punishment is cruel if it is too long or too harsh for the crime. This must also consider what society sees as right as time goes on.

Second, for how people in prison are treated, including their living conditions, courts check if the treatment causes "needless and harsh pain." This means that the prison conditions must take away "basic human needs" so much that they cause harm or a "big risk of serious harm." Also, prison staff must have "known about" this risk and done nothing. Courts also think about whether the prison has a good reason for the condition, like keeping order.

Even with these rules, solitary confinement itself is not seen as cruel and unusual punishment. It only becomes cruel if the conditions cause harsh and needless pain. Courts have often looked at solitary confinement cases in a very narrow way. This has led to concerns that they do not give enough thought to the general mental pain caused by being alone for a long time.

Solitary Confinement and Basic Needs

Courts often think of "basic human needs" as things like food, water, a place to sleep, exercise, medical care, and clean conditions. These are mostly seen as physical needs for survival. The Supreme Court has also said that only "extreme losses" of these needs are enough to be a problem. This means taking away the "minimum basic things for life."

This narrow view of "basic human needs" makes it hard to challenge solitary confinement. If a person in isolation still gets basic survival items, even harsh conditions might not be seen as cruel.

The hurdle is even higher because the loss of basic needs must cause a "big risk of serious harm." Courts are not always clear if this harm has to be physical or mental. But often, "serious harm" is seen as physical harm, like not having food, water, or clean conditions, which leads to physical problems.

One exception is when people with mental health issues are put in solitary confinement. Courts have said this can be unconstitutional because mental illness makes people more likely to be harmed by isolation. But even then, courts have often said that most people in prison are strong enough to handle isolation without severe mental harm. This means they do not see solitary confinement as always violating the rules for everyone.

This way of thinking misses the point that being alone for a long time can cause serious mental harm to anyone, not just those with mental illness. It downplays how much mental damage extreme isolation can cause.

Solitary Confinement and Staff Responsibility

Courts have said that for prison conditions to be cruel, prison staff must have "known about" a serious risk to a person's health or safety and ignored it. This means staff must have understood there was a big risk of serious harm and still done nothing. It is like saying if they did not know about a risk they should have seen, it is not considered punishment.

This rule about staff responsibility has been criticized. It can be hard to prove that prison staff purposely ignored harm, especially mental harm. Staff may not be trained in mental health and might say they did not know about a prisoner's mental health needs. It is easier to prove if staff ignored physical problems, which are clearer to see.

Many people think this rule should be changed or removed, focusing only on the prison conditions themselves. For solitary confinement, some say that just putting someone in extreme isolation should be enough to show that staff ignored the person's health and safety.

Reasons for Punishment

Courts also consider if the prison has a "good reason" for keeping a person in a certain condition. This means looking at the prison's needs for discipline, security, and safety. If solitary confinement is seen as good for these reasons, it can balance out the harm it might cause.

Many prison leaders believe solitary confinement helps keep prisons safe and orderly. They think it stops crime and violence inside. So, the idea is that the good things solitary confinement does for the prison outweigh the bad things it does to the people in isolation.

Courts often let prison leaders make these decisions because they are seen as knowing best how to run prisons and keep them safe. This means courts usually trust what prison staff say about why solitary confinement is needed. For example, a court might say that even if someone is suffering mental pain in solitary, prison staff need to control dangerous people.

However, critics say that prison staff do not always have to give strong reasons for solitary confinement. Saying they need to house the "worst of the worst" often seems to be enough. This often leads to courts not looking closely at the actual conditions of solitary confinement. Even though courts have said that they should look at how punishment affects the person, the prison's reasons often win out over concerns for the people held there.

Mental Pain from Being Alone

Many studies have shown the mental effects of solitary confinement. Being alone in a small, empty space can cause serious mental harm, like thoughts of suicide, sadness, and problems with memory. Even without the most severe issues, being alone can cause feelings of social pain, like feeling left out or worthless. This can also lead to bad physical and mental health, anger, and less self-esteem.

Even though these studies are well-known and have been presented in courts, judges have rarely said that mental harm from isolation is enough to violate the rules against cruel punishment. Courts often do not see mental suffering as a reason to act.

There are two main reasons for this. First, courts tend to see "basic human needs" as physical needs, like food and water, not the need for social contact. Only sometimes do they see social interaction as a basic need.

Second, the harm from not having social contact is mental, not physical. In the U.S., mental harm is often seen as less important than physical harm. Laws like the Prison Litigation Reform Act even say that you usually need proof of physical injury to sue for mental or emotional harm in prison. This has made it harder to challenge the mental suffering caused by solitary confinement.

So, because courts do not see social interaction as a basic physical need and see mental harm as less important, they often treat solitary confinement the same as regular prison time. If the basic physical needs are met, they often do not see a problem.

How Long People Are Kept Alone

The little importance given to mental pain is connected to another issue courts often overlook: how long someone is kept in solitary confinement. There are no uniform rules across states for how long someone can be kept alone. Prison leaders usually decide, meaning solitary confinement can last a few days, a very long time, or even forever.

Courts, including the Supreme Court, have rarely looked at the length of solitary confinement as a standalone problem. Instead, they usually consider it along with the actual living conditions. So, if the living conditions are bad, then the length might matter, but not on its own.

Lower courts have sometimes been more open to looking at how long someone is isolated. For example, some courts have tried to set limits, like no more than 15 days, or said that even acceptable forms of solitary confinement could be unlawful if they last too long.

However, the Supreme Court has been less likely to say that the length of solitary confinement matters on its own. They have often said that being put in solitary for a long time is fine if the conditions are not much different from regular prison. They also trust prison leaders to decide how long people need to be isolated.

But recently, there has been more concern about long-term solitary confinement in lower courts and even in the Supreme Court. Some courts have said that being alone for a very long time can indeed violate the rules. For example, one court agreed that stress from isolation can be as bad as physical torture. A Supreme Court Justice also said that long isolation raises serious questions, no matter the conditions, and that courts should look into it more, instead of just trusting prison leaders.

Another Justice also shared "deep concern" about the extreme mental pain caused by long-term isolation. They pointed out that while in the past people might not have known how much solitary confinement hurt people, "Today, we are no longer so unaware." This shows a growing push to change how courts view long-term solitary confinement. But even these recent views still do not fully focus on the core problem: being alone itself.

The Brain in Solitary

Courts often see solitary confinement and regular prison time as mostly the same. They believe that unless the actual living conditions are bad, solitary confinement is fine. This means that being alone, or lacking social contact and things to do, is not seen as a reason to say it is cruel punishment.

But recently, new science about the brain is being used to challenge solitary confinement. This science looks at how the brain changes and how important social contact and things to do are. It also shows what happens to the brain when these things are missing. These studies have been used in some court cases to show the harm of extreme isolation. The main idea is that the mental problems from being alone are linked to changes in the brain. These brain changes can have long-lasting or even permanent bad effects.

This new brain science can offer fresh support to challenges against solitary confinement. We will look closer at this by reviewing scientific facts, many of which have been used in court. This will show three main arguments:

1. Being with others is a basic physical need, like food or water.

2. Being alone and having nothing to do causes serious changes in the brain that can lead to lasting mental problems.

3. The pain of being alone is real and physical in the brain.

Why We Need Social Contact for a Healthy Brain

Long ago, a famous thinker said that humans naturally want to live together. Thousands of years later, science has shown that humans are built to connect with each other. Experts in many fields now agree that social connection, interaction, and feeling like you belong are basic survival needs for humans, just like food or water.

One important study showed that people are wired to form strong, lasting relationships because they have an inborn need to belong. This need is met by having regular contact with others and truly caring relationships.

The study listed nine signs that something is a basic human need. Social connection meets all of these. This means it affects our feelings, how we think, and our health. If we do not have it, it causes problems. It is something all people need, it is not just from other wants, and it affects many behaviors.

Other research supports this. Social interaction helps our brains develop and use thinking skills. Being involved in social activities helps older adults keep their thinking sharp. Studies also link social connection to better physical and mental health and a longer life. Good social connections also help people learn social skills like empathy.

Our brains show how important social contact is. Our brains are big because they help us deal with complex social interactions. One expert says the brain is a "social organ." It helps us understand and respond to others, keeping us connected. Also, social interactions, from talking to touching, constantly shape how our brains work.

Studies on brain changes show that good social interaction makes positive changes in brain areas that control thinking, social skills, and behavior throughout life. These changes are linked to better thinking, mental well-being, and being more social.

Research on how the environment affects the brain also matches this. Studies on animals show that those raised in rich environments with other animals have normal brain development and social behavior. This includes growth of new brain cells in areas important for social interaction and memory. But being alone and having nothing to do seems to stop this growth.

In short, our brain and our social world are deeply linked. Our brain helps us connect with others, and our social world helps our brain work well. So, social contact in stimulating places is key for brain health. One expert said, "No one will die from lack of social contact over a few days, but people will show evidence of being in a deprived state within a short period and a lack of social connection will likely produce a wide array of negative outcomes for an individual’s mental and physical well-being before long." This means that without social and environmental connections, the brain and the person will likely suffer serious harm over time.

The Brain Effects of Being Alone and Having Nothing to Do

Many studies have looked at what happens to people in solitary confinement, both those with and without mental health issues. All these studies point to the same serious conclusion: solitary confinement can cause lasting damage to thinking, emotions, and the body.

For example, one doctor found three main mental problems in people in solitary: seeing things that are not there, feeling anxious and having panic attacks, and having unwanted thoughts that sometimes lead to repeating actions. He said that some people might even have serious mental breaks, while others still suffer from deep anxiety, paranoia, and anger.

Other studies have also linked solitary confinement to many bad mental effects, like extreme anger, fear, lack of self-control, deep sadness, loss of appetite, and feeling distant. It also takes away a person's sense of belonging, self-worth, and identity. These effects are linked to a higher chance of bad, anti-social, and harmful behavior.

It is important to note that these mental problems often continue even after a person leaves prison and goes back to society. People who have been in solitary confinement struggle to adjust to normal life. They might be too sensitive to everyday sounds and unable to take part in family activities.

Science is now starting to find the brain changes that go along with these mental problems caused by being alone and having nothing to do. For example, brain wave studies show that even a few days in solitary confinement can cause brain changes similar to an injury. These changes are linked to being too sensitive to outside things, not paying enough attention, and a loss of a person's sense of self.

These findings are backed up by many animal studies, which help us understand the brain processes behind the mental issues seen in people isolated for long periods. These studies show that being alone and in a boring environment hurts both the brain's structure and how it works. This includes less brain volume, fewer brain connections, and changes in areas that control rewards and emotions. These brain changes have been linked to feeling cut off, being hostile, being very aggressive, and a higher risk of mental problems similar to those in humans, like brain diseases and schizophrenia. Importantly, these brain changes can happen quickly and seem to continue even after the animal is put back in a social environment.

Many studies have looked at how long-term stress from being alone affects the brain. For example, studies on rats show that those housed alone have smaller brains and fewer connections in areas important for memory, social information, and managing emotions, compared to rats in rich environments. These brain damages have been linked to long-term mental health problems in humans, like memory loss, thinking problems, sadness, and PTSD.

Another brain area affected is the amygdala, which deals with emotions like fear and anxiety. Studies show that high stress increases certain chemicals, which change brain cells in the amygdala and lead to anxiety, problems with social interaction, and poor control over social behavior.

In the outer part of the brain, studies on isolated rats showed less of a substance called myelin, which helps brain signals travel. Problems with myelin have been seen in mental illnesses like anxiety, autism, schizophrenia, and depression. Other rat studies showed that isolated rats had a smaller prefrontal cortex, a brain area linked to many symptoms of schizophrenia in humans, like fear of new things and memory issues.

Studies on feeling lonely, which is the feeling of being isolated, also connect to these findings. Even if someone is not physically alone, feeling lonely can cause problems. Research on loneliness shows it is linked to "poorer overall cognitive performance, faster cognitive decline, poorer executive functioning, more negativity and depressive cognition, heightened sensitivity to social threats" as well as "increased anxiety, hostility, and social withdrawal; … decreased impulse control; increased negativity and depressive symptoms." Also, studies have shown links between the signs of loneliness and the brain changes seen after being physically isolated.

Overall, there is strong evidence that being alone and having nothing to do causes harmful and lasting brain changes. This evidence suggests that many of these effects are hard to undo, even after a person returns to a social setting. While more research is needed to fully understand all the effects, the current evidence is clear: "increased social isolation and diminished physical contact contribute to and reinforce problematic neurobiological patterns." This means the conditions of solitary confinement will likely "create or make worse brain problems and bad behaviors." This is especially true for people who commit crimes often, as their existing brain weaknesses are made worse in isolation, leading to more bad behaviors. All in all, brain science shows that the main parts of solitary confinement—being alone and having nothing to do—can cause serious brain damage on their own. These damages risk causing lasting or even permanent mental and physical problems. So far, courts have mostly overlooked these issues.

Social Pain Is Physical

One important finding from brain science about the effects of being alone is about "social pain." Most people and even the law often think that physical pain (from a body injury or not having a physical need) is different from social pain (mental pain). Physical pain is seen as real, measurable, and clear. Social pain, on the other hand, is often seen as purely mental, subjective, and not truly "real." Because of this, it is often ignored as just an internal feeling with no real effects. This idea of different types of pain is seen in how courts deal with solitary confinement. But more and more brain research is showing that social pain is deeply real in the brain. It is, at its core, physical.

A main idea, called the shared representation theory, says that physical pain and social pain "use the same brain circuits." This means that social pain comes from the natural human need to connect and belong. From an evolutionary view, this need likely comes from the long time baby mammals need care from their mothers to survive. Not getting these basic needs causes a feeling of rejection, which feels painful and stressful. Because of this survival need, it is possible that "the social attachment system—which ensures social connection—may have piggybacked directly onto the physical pain system, borrowing the pain signal itself to indicate when social relationships are threatened." So, feeling social pain might be a way for us to adapt and avoid the threat of being rejected. As two experts put it, "just as evolution has wired us to feel pain when we lack food (e.g., hunger), water (e.g., thirst), or shelter (e.g., freezing, sunburn), perhaps evolution has wired us to feel pain when we lack... social connection."

Following this idea, brain imaging studies have shown that physical pain and social pain activate many of the same areas in the brain. Specifically, physical pain has two parts: a sensory part (where you feel it in your body) and an emotional part (the distressing feeling of pain). Studies show that social pain activates the brain areas involved in the emotional part of physical pain. These studies also show that people who are more sensitive to physical pain are also more likely to feel social pain. Things that help physical pain also seem to help social pain.

Social pain has been linked to both being physically alone (not having social contact) and feeling lonely (the feeling of isolation). Lab studies have looked at the link between social pain and being disconnected socially, by looking at brain activity in the areas that handle this type of pain. These findings might explain why people who are more isolated, either truly or in feeling, have a higher risk of physical and mental health problems, and even a higher risk of dying sooner. As one expert explained, since certain brain areas are involved in responding to social disconnection, they "may have a role in translating experiences of social disconnection into downstream physiological responses—such as heightened inflammatory activity, the immune system’s first line of defense against foreign agents and infection." Increased inflammation has been linked to negative physical and mental health issues, like heart disease and sadness.

Lastly, these brain imaging studies have also started to look at how social pain affects aggression. Early results show a link between more activity in these pain-related brain areas (from social pain) and more aggression in people who feel rejected and have less control over their actions. This suggests that social pain can lead to aggressive reactions in those who feel left out.

While some studies have found slight differences in how the brain processes physical and social pain, the overall message from brain science about social pain is clear for this article. First, not having social connection – being alone – causes many bad feelings, mental problems, and poor behaviors. These are linked to the pain of being left out or rejected. Second, this social pain is physically real in the brain. It should be seen as "real pain," not just a "metaphorical pain." Importantly, social pain is not less serious or less harmful than physical pain. In fact, its effects on a person can be more distressing and damaging. So, it is wrong to treat physical pain as more important than social pain. This ignores the intense suffering that social pain from isolation can cause, which can be just as strong, traumatic, and long-lasting as physical pain from lacking a physical need.

Solitary Confinement Is Always Cruel and Unusual Punishment

The new brain research showing how vital social interaction is for brain health, along with what happens when people are isolated, could restart efforts to challenge solitary confinement.

While we need more exact answers about all the ways solitary confinement affects the brain and behavior, the current evidence strongly supports challenging the core of solitary confinement: extreme isolation. The science showing the traumatic effects of extreme isolation matches what many international groups have said: "all forms of solitary confinement without appropriate mental or physical stimulation are likely, in the long term, to have damaging effects."

Based on this, this article makes three main points for arguing that solitary confinement, as it is used in many places today, always violates the rules against cruel and unusual punishment. First, the main feature of solitary confinement—extreme isolation or not having social contact and things to do—does not meet the current standards. Second, the serious and possibly lasting harm from being alone does not balance out the prison's reasons for using solitary confinement. Also, solitary confinement goes against all the reasons we punish people. If solitary confinement fails to meet these rules, it means it is naturally unconstitutional.

It Does Not Meet Current Standards

The brain research on what happens when people are isolated shows a strong reason to argue that being isolated (the main part of solitary confinement) should always be seen as cruel and unusual punishment under current court rules. This section explains each part.

Social contact and things to do are basic human needs.

Following what we know about how humans developed, brain research strongly shows that social interaction is a basic human need for survival, just like water, food, or shelter. As discussed, social interaction is simply part of human nature; we are social beings. This comes from the deep connection between our brains and our social world. Also, the brain's need for social interaction is completed by the need for things to do in our environment. As explained, a stimulating environment greatly helps brain development and behavior, and the human brain needs many different signals from the outside world to work properly. All the evidence shows that social interaction and a stimulating environment are necessary for a healthy brain. So, taking away social contact and environmental stimulation is like taking away what makes us human.

If we agree that social interaction in rich environments is vital, then forcing people into tiny, boring cells is enough, on its own, to take away basic human needs. This means that other bad conditions in solitary confinement (like no heat or bad beds) should be seen as making an already bad situation worse, not as the main problem. The main problem is the extreme isolation itself.

Importantly, if social interaction and environmental stimulation are seen as basic human needs, it challenges the idea that regular prison and solitary confinement are the same. Courts have said solitary confinement is fine as long as its conditions are not much different from regular prison. But this view misses that extreme isolation is what makes solitary confinement very different. This difference comes from solitary confinement taking away a survival need that regular prison provides. Because of this key difference and its effects, regular prison and solitary confinement cannot be treated the same. Solitary confinement should be judged by its own rules, which must always see social interaction as a basic need, not just a privilege.

Being isolated carries a serious risk of physical harm.

If the vital role of social interaction and a stimulating environment for the human brain and behavior is not enough to prove they are basic physical needs, then the evidence of risks that being isolated puts on the brain gives strong reasons to rethink the "big risk of serious harm" rule for solitary confinement.

As discussed, the brain changes or damage that happens from being isolated seem to be behind many bad thinking, emotional, and behavior patterns. These changes have also been seen in major mental health problems like sadness and schizophrenia. These findings support the many existing studies that have shown the severe mental and emotional effects of solitary confinement. Also, the brain and mental damages from being isolated have been found to cause physical health problems and even increase the risk of dying sooner. From this view, the serious damage that solitary confinement could cause to people in prison can be long-lasting or even permanent.

Just as important is what we know about social pain from isolation. Besides showing that social pain is physically real, brain research has also strongly suggested that feeling social pain can be much worse than physical pain in many ways. Social pain has been linked to many mental problems, including feeling ashamed, low self-esteem, bad ways of acting (like aggression), and poorer physical and mental health, especially in the long run. So, even if the painful effects of social pain are not immediately clear, they can appear and get worse over time.

Turning brain science into legal terms, we can make these points. First, being isolated does create a very serious risk of physical harm, similar to not having food or sleep. Even if the harm solitary confinement causes the brain leads to mental problems, it is also clear that "the type of severe psychological deterioration observed in solitary confinement is due to physical harms imposed on the brain." So, it is ultimately physical.

Second, the harm solitary confinement causes to the brain leads to many long-lasting or possibly permanent mental, physical, and body conditions. So, the possible harms of solitary confinement are not only disfiguring but also potentially permanent. Lastly, and maybe most importantly, the risk of these physical harms can show up even after a short time of extreme isolation. As mentioned, science has not yet figured out exactly how long a person can be isolated without getting irreversible brain damage. But experts agree across different sciences that the longer someone is isolated, the higher the risk they will suffer damage to their brain, body, mind, and physically.

Of course, not everyone will suffer irreversible damage, and not everyone will have the same traumas after the same amount of time. But as one expert correctly said, "The fact that serious risks may never materialize in serious harm (or that harm may not be imminent) is not conclusive for... the test." Also, the risk of serious brain and mental damage from solitary confinement is universal: anyone can be affected, no matter if they have a history of mental illness.

Given these points, solitary confinement alone also meets the "big risk of serious (physical) harm" part of the rules. By taking away a basic need for life, solitary confinement itself risks causing needless suffering that is marked by serious and potentially permanent effects. As the Court has often said, how we understand the rules changes as society learns more and its ideas of what is decent evolve. A punishment that risks causing serious and potentially permanent damage to people goes against what society considers decent today. No civilized society should allow such harm to be done to humans.

Ignoring Harm Comes from Extreme Isolation

As noted earlier, the rule about prison staff purposely ignoring harm has been criticized, especially in solitary confinement cases. It can be very hard to prove that prison staff or leaders knowingly ignored the harm caused by taking away basic human needs from people in prison. This difficult proof can stop fair claims based on the harmful conditions of solitary confinement.

Courts have agreed that if the risk of serious harm from a prison condition is clear and widely known, that clear proof is enough to show that prison staff knew about it. For solitary confinement, some court opinions have questioned the need for direct proof of ignoring harm because putting people in solitary confinement clearly creates a big risk of serious harm. For example, one court said that "common sense shows that 'lack of exercise, social isolation, and/or stress are associated with [harmful] conditions.'... [Therefore, a] court 'may infer the existence of this subjective state of mind [i.e., purposely ignoring harm] from the fact that the risk of harm is obvious'." Similarly, Supreme Court opinions have noted the growing awareness of the harms of solitary confinement in U.S. prisons. These harms have been well-documented by science, law, and international groups.

Furthermore, some experts have argued that in cases where courts can order changes, there should be a rule that assumes prison staff are at fault. For example, it has been suggested that "prisoners could certainly show by the time of trial that authorities were aware of either the actual harm or risk of harm caused by solitary confinement." So, if harmful conditions are allowed to continue, courts can assume prison staff knew about them from the conditions themselves, without needing direct proof of their thoughts.

This article's ideas further strengthen these claims. If we recognize that the main condition of solitary confinement, which is extreme isolation, itself causes needless and harsh pain and is cruel and unusual punishment, then the rule about staff purposely ignoring harm becomes unnecessary. Given the growing general awareness of the clear harms linked to solitary confinement, showing that someone was isolated is enough to conclude that prison staff ignored harm. This is because putting someone in extreme isolation is essentially taking away a basic human need and carries a clear and well-known risk of serious harm. Therefore, a judge or jury could decide that by keeping someone in solitary confinement despite the obvious health risks, both physical and mental, the prison staff purposely ignored the big risk of harm.

It Does Not Meet Its Goals

The evidence about the general problems caused by solitary confinement also overturns the idea that the "pains" of solitary confinement are balanced by the prison's needs for discipline, security, and safety. This "new" imbalance comes from the fact that being isolated, especially for a long time, risks causing severe brain damage, even in people without mental illness. These damages might not stop when the person is in isolation. Given the long-lasting mental problems they cause, the effects of this damage risk continuing even after a person goes back to a social setting, whether it is the prison or the general public. The risk of brain damage from extreme isolation is too high—and therefore very unbalanced—for any reason to possibly justify it.

These claims support the strong evidence showing that neither short-term nor long-term solitary confinement actually stops future rule-breaking or prison incidents. Instead, evidence shows that solitary confinement seems to have the opposite effect. Also, places that have limited the use of solitary confinement have seen less prison violence. So, limiting solitary confinement does not make prisons less safe and might actually make them safer.

Acknowledging these claims might make courts rethink their (often too strong) willingness to let prison leaders manage and use solitary confinement. Specifically, it might make courts look closely at the "good reasons" prison leaders give to defend using solitary confinement. This could fully bring back the protection for people in custody that is at the heart of the Eighth Amendment.

More broadly, when looking at the reasons for a prison condition or practice, courts should consider new knowledge and how society's ideas of decency change over time. Today, many groups at home and abroad disagree with solitary confinement, suggesting that ideas of decency have moved away from using it for its intended goals. More knowledge also shows that less restrictive and less painful methods are more effective for the same goals. So, no prison reason can justify the widespread and unthinking use of solitary confinement. Also, no prison reason can outweigh the damage that solitary confinement risks causing to people in prison. Of course, solitary confinement might still be needed for temporary protection or for the most serious violent acts, but only after other options have failed. Even in these cases, separating a person from others in the prison can still be done in a kinder and less restrictive way.

Solitary Confinement and the Goals of Punishment Do Not Mix

Solitary confinement and its effects also do not fit with the goals of punishment: making people pay for their crimes, keeping them from harming others, stopping them from committing future crimes, and helping them become better. As such, it has no real purpose in punishment. While courts do not usually look at these broader punishment goals when dealing with solitary confinement cases, explaining why solitary confinement goes against each goal can still be helpful.

First, let's look at making people pay for their crimes. This usually involves two parts. First, an objective look at how serious the crime was. Second, a look at how much the person is to blame, including things like their age or mental abilities. So, from this view, a punishment is too harsh if it is too severe for the crime and how much the person is to blame.

For this article, we also look at another key part of this idea: treating people who commit crimes as thinking, moral beings. This is central to any punishment that aims to make people pay for their crimes. This idea assumes that the person understood what they were doing and chose to break the law. Based on this, such punishment aims to make sure people "are capable of understanding the wrongs they have committed and the fairness of the penal sanctions imposed on them by the state in response to those wrong." So, this view insists on structuring legal punishment to at least treat offenders as thinking, moral beings.

This view says that prison takes away people's freedom by greatly limiting their ability to live on their own. But it does not say that prison should also destroy the things that make someone a moral person, like "physical and psychological health, work and interaction with others." From this view, these abilities need to be used regularly so people in prison can "understand and respond constructively to the reasons for which they are being punished."

From this way of thinking, solitary confinement does not fit. It risks causing serious brain and mental damage to people in prison. These damages hurt the thinking and emotional abilities needed for making good choices and "cause further atrophy of what may have already been weak capacities to identify with and feel for others." Also, the lasting or even permanent physical, mental, and body damages from solitary confinement can continue even after a person's sentence is over. So, solitary confinement, which can cause lasting or permanent losses, makes a prison sentence too harsh for the crimes committed. This goes against what this type of punishment is meant to do.

Solitary confinement also fails the goals of punishment that look at the results, like keeping people from harming others, stopping future crimes, and helping people change. Keeping people from harming others means prison removes people from society so they cannot commit more crimes. Solitary confinement, especially in high-security prisons, does this during the time a person is held. But we also need to look at if solitary confinement actually stops future crimes.

Ideas about solitary confinement often stress that it can stop people from committing future crimes. But evidence shows that solitary confinement does not work to stop people from reoffending or change their behavior. In fact, people in solitary confinement often do worse after they are released than those in the general prison population. For example, one study found that solitary confinement was linked to a higher risk of formerly incarcerated people committing a violent crime after release. Other studies have found the same thing. The reasons for this higher risk also come from the brain changes caused by solitary confinement, which are linked to bad mental problems and health issues that are known to lead to bad social behaviors, including anti-social acts.

Lastly, solitary confinement does not help people become better. Helping people change aims to get them back into society after prison so they can live law-abiding and self-supporting lives. It tries to rebuild good relationships between people who committed crimes and the rest of society by helping them change and improve through relationships. Helping people change means encouraging as much inclusion and positive social contact as possible while people are in prison, as this can help them get back into the community.

Besides going against the values and goals of helping people change, the possible harms of solitary confinement, like being more prone to aggression and other bad mental and behavioral patterns, can seriously hurt a person's ability to function in society. So, these harms seriously get in the way of the process of changing and getting back into society, making it harder, or even almost impossible, in some cases.

To sum up, the type and amount of harm that solitary confinement can cause people do not fit with any reason for punishment. So, solitary confinement causes needless and harsh pain because it not only takes away people's basic needs for social and environmental connection but also has no real purpose in punishment. The suffering it causes is needless and goes against all relevant ideas under the Eighth Amendment. No reason or goal for punishment can justify inflicting it; solitary confinement is, by its very nature, cruel and unusual punishment.

A Way Forward: Ending Solitude in Prison

The arguments in this article lead to the conclusion that solitary confinement, as it is still used in many prisons or justice systems, should be completely stopped. This idea matches what many groups, movements, and organizations around the world have called for: ending solitary confinement or at least using it only in very rare and carefully controlled situations.

Separating a person in prison from others should always be a last resort. It should only be used for extreme situations—which must be clearly written down by prison staff and ideally overseen by special committees—and only when absolutely necessary to meet important prison goals. In such cases, separating someone should follow strict rules about how long, how much social contact, and what kind of environment is allowed. These rules (which should be the same everywhere) are needed to fight against arbitrary uses of solitary confinement and a legal weakness that allows prisons to use solitary confinement with little court oversight.

Regarding time limits, one survey showed times ranging from a few days to over six years in different places. While fewer people were in solitary for short times, many more were held for at least one month to over six years.

More research is needed to find the exact maximum time a person can be isolated without causing lasting harm. However, knowing that being isolated risks causing or worsening physical, body, and mental problems after just a few days is enough reason to set uniform maximum time limits. These limits should match what we know from science and international guidelines. Since there are currently few court decisions on time limits for solitary confinement, the strong international and national guidelines suggesting a maximum of 15 days in solitary confinement should be used as a standard for all places. All states should follow these rules, and breaking them should be seen as a violation.

Besides setting uniform time limits, uniform rules for social contact are also needed. The same survey also reported good results from places that have recently set rules to limit solitary confinement to only the most serious cases, to improve the "social" conditions for people held alone. Some places have policies that allow more time out of cells, outdoor activities, classes, job training, rehabilitation, and programs to help people get back into society. However, only a few have allowed more visiting time. Some policies even train prison officers to use other ways to deal with prison violence that focus on talking, being responsible, and working together. Notably, statistics show that prison incidents and the overall rate of reoffending after release have both gone down. These small changes are encouraging and show a growing understanding that solitary confinement is not helpful and can be very damaging. Making sure all prisons adopt and follow social contact rules—including recreation, education, rehabilitation programs, and visiting hours with important people—for people temporarily separated from others is vital to fight the bad effects of isolation and help them get back into society.

Finally, while this applies to all prisons, the design of isolation cells should follow strict environmental rules. Courts have said that "the Constitution does not demand comfortable prisons." But it also said that the Constitution "neither does...permit inhumane ones." The studies mentioned earlier show that surroundings—whether rich or poor—greatly affect brain structure and function, as well as mental well-being and social behavior. Tiny, empty cells risk making the negative effects of not having social contact even worse.

Several experts have called for making prisons as humane and home-like as possible. Good examples from other countries show that home-like cells with natural light, even in high-security prisons, where people in prison have things like proper beds, furniture, or reading materials, help with their physical and mental well-being. This overall well-being has been found to help reduce bad behavior in prison and the overall rate of reoffending.

It is likely hard to expect such a big change in U.S. prisons right away. However, it is important to know that such good ways of doing things exist and work. Most importantly, those ways show an important lesson of "dignity and humanity that is the birthright of every person, and... respect [for] the collective dignity and humanity of society." These are the values and rights that are behind the rules against cruel and unusual punishment, and they should also lead to ending solitary confinement.

Conclusion

In her thoughts on a court case, one Justice wrote, "A punishment need not leave physical scars to be cruel and unusual." However, not having social contact or things to do can clearly leave many scars, which might even be visible. Solitary confinement is a harmful and dehumanizing punishment because it takes away people's basic needs, greatly changes their bodies, and causes severe mental and physical harm. It is increasingly the right time to fix the many, possibly lasting scars that solitary confinement can cause people in prison. Continuing to ignore these scars will only make them worse.