Seeing Solitary home

Glossary & FAQ

solitary confinement cell
Photo courtesy of the ACLU
Individual cages used for those in solitary confinement to have outdoor recreation time at Arizona State Prison Complex, Eyman, 2021

Isolated housing conditions exist under different forms and different names in detention facilities throughout the United States and around the world. As explained on the Methodology page, the surveys from which the data were drawn for this website:

  • Only asked about prison facilities – not jails, juvenile detention, immigration detention, or other facilities that hold detainees.
  • Only went to the state and federal prison systems in the United States.
  • Defined solitary confinement – or "restrictive housing" – as conditions in which a person is isolated in a cell for an average of 22+ hours per day, for 15 consecutive days or more.
  • Do not report on individuals held in isolation for fewer than 22 hours per day, for fifteen consecutive days or more. In addition, no research study can substitute for the experiences of individuals put into isolation. You can read some first-hand descriptions of solitary confinement on this website here.

Prison systems have information about people in their facilities and not people held in local jails or other jurisdictions. To get the best information possible, we asked prison systems to tell us about their "total custodial population,” defined as "the total number of people sentenced to and received by" a corrections department and under that department’s "direct control." Those totals include people held at any level of custody, from solitary confinement to the least restrictive setting. The "total custodial population" is not synonymous with the term "general population," which is a classification that refers to a subset of people who are not held in a more restrictive setting.

The 2021 CLA-Liman Survey asked the 50 states and the federal government to report the number of people in prison solitary confinement and under their direct control. The 35 jurisdictions that responded reported a total of 25,083 in solitary. To estimate the number of people in solitary confinement in prisons throughout the United States – including jurisdictions that did not respond to the survey – we needed to know the number of all the people (including those under the "legal authority" of the thirty-five restrictive housing responding jurisdictions but not under their “direct control”) and the number of people held by jurisdictions that did not answer the survey to provide information on individuals in solitary confinement. To do so, we relied on data that the Vera Institute (Vera) gathered regarding the number of people imprisoned in the U.S. as of March 2021.

  1. The 2021 CLA-Liman Survey asked jurisdictions to report information about people under their "direct control" because, when jurisdictions send individuals out of state or to facilities otherwise not under their direct control, they generally cannot report (or control) whether those individuals are in solitary – even though they are incarcerated under the jurisdiction’s authority. For this reason, a jurisdiction’s "total custodial population" under the 2021 CLA-Liman Survey is frequently less than the number of people the Vera Institute recorded as incarcerated under the authority of that jurisdiction.

Vera’s March 2021 data reported that, in the thirty-five jurisdictions that responded to the 2021 CLA-Liman Survey, 802,821 people were under their "legal authority" – 71,619 more than reported to be under their direct control as of July 2021. 2. Fifteen jurisdictions did not respond to the 2021 CLA-Liman Survey, and one jurisdiction responded to the Survey without providing information on the number of people in restrictive housing. Vera’s March 2021 data indicated that these sixteen jurisdictions had 391,113 people under their legal authority.

Thus, given these 71,619 and 391,113 people, the 2021 CLA-Liman Survey did not gather data about 462,732 people imprisoned in the United States. To estimate the number in solitary confinement in U.S. prisons, we turned to what we learned from the jurisdictions that had responded. The thirty-five responding jurisdictions reported that 3.4% of the people they held were in restrictive housing. If the jurisdictions that did not respond were like those that did, then 3.4% of the 462,732 incarcerated people—or 15,733 individuals—for whom no data was provided would have been in solitary confinement. Yet, as social scientists term it, "selection bias" may be at work; the thirty-five responding jurisdictions may use restrictive housing less than those that did not respond. Of the sixteen jurisdictions that did not respond to the survey in 2021, eleven had responded in 2019, and those eleven reported a weighted average of 5.0% of people in solitary confinement. If 5.0% of the 462,732 imprisoned people about whom we did not have data were, in July of 2021 in solitary confinement, a total of 23,137 people would have been in those conditions. We therefore used 3.4% (15,733) as a minimum and 5.0% (23,137) as a maximum to add to the number reported—25,083—so as to estimate that the total number of people who would have been reported to be in solitary confinement in U.S. prisons as of July 2021 was between 41,000 and 48,000. Again, the reminders are that people held 21 hours for months or years or held for fewer than 15 consecutive days are not represented in this estimate. The surveys are the only decade-long data available on solitary confinement, and we used the information collected in 2013 as a starting point and this 2021 estimate as an endpoint to consider changes. The 2014 report estimated that between 80,000 and 100,000 people were in isolation in prisons as of the fall of 2014. The 2017 Survey estimated that 61,000 people were held in isolation in prisons as of the fall of 2017. The 2019 Survey estimated that between 55,000 and 62,500 people were in restrictive housing as of the summer of 2019, and the 2021 Survey estimated that 41,000 to 48,000 people were in isolation. Based solely on these years of self-reports, we therefore estimate that U.S. jurisdictions reduced the number of people held under the definition of solitary that was for an average of twenty-two hours or more per day, for fifteen consecutive days or more.

One reason to gather data was to learn what was happening and another was to see whether that information could help bring about change. With the reminder that the data collected are based on self-reports by prison systems, the numbers of people held were less than were reported about a decade ago. To the extent the numbers of people in restrictive housing were decreasing, a variety of factors could be contributing to that change. One key variable is the total national prison population. Between the 2014-2015 Survey and the 2021 Survey, the total prison population in the United States declined from approximately 1.6 million people to 1.2 million people. The decline was not uniform across the fifty states and the federal system. In addition to shifting rates of incarceration, between 2020 and 2022 COVID-19 had an impact. Some parts of the criminal law enforcement system slowed down. In some places, prosecutors did not pursue or delayed their cases, some courts closed, and some judges focused on alternatives to incarceration or postponed imposing sentences. A January 2022 analysis of the impact of COVID-19 reductions in imprisonment determined that “incarcerated white people benefited disproportionately from this decrease in the U.S. prison population, and the fraction of incarcerated Black and Latino people sharply increased.” Other sources of changing numbers in solitary confinement are the policies issued by correctional systems governing solitary confinement. For example, the American Correctional Association (ACA) in 2016 issued new Restrictive Housing Performance-Based Standards. Those rules defined extended solitary confinement as “confined to a cell at least 22 hours per day” for at least 30 days, and prohibited such placement for individuals with serious mental illness. The standards also instructed prison systems not to use extended solitary confinement for incarcerated people who are pregnant or under age 18, nor to place individuals in solitary confinement solely on the basis of gender identity. As reported in the data on this website, four jurisdictions sought to end the use of isolation for fifteen days or more: Colorado, North Dakota, Vermont, and Delaware. For example, in both the 2019 and 2021 surveys, the North Dakota Department of Corrections and Rehabilitation reported holding zero people in restrictive housing for 22 hours per day for fifteen days or more – down from more than 100 people in 2015. See Time-in-Cell 2019: A Snapshot of Restrictive Housing. In 2012, when the Liman Center began this work, few statutes addressed solitary confinement. By 2020, several state and federal legislatures imposed limits on the use of solitary confinement and/or required reporting about it. Details on legislative activity can be found in Reforming Restrictive Housing: The 2018 ASCA-Liman Nationwide Survey of Time-in-Cell. This website’s Legislation page also provides more information about legislative activity throughout the country. In some jurisdictions, litigation has been the catalyst for change, as lawsuits have led to policy change and limitations on the use of solitary confinement. In 2019, the Fourth Circuit Court of Appeals held in Porter v. Clarke that placing individuals “alone, in a small . . . cell” with “no access to congregate religious, educational, or social programming” in Virginia prisons “posed a substantial risk of serious psychological and emotional harm” and “State Defendants were deliberately indifferent to that risk.” Often, settlement agreements are not a clear path to change. In 2015, in Ashker v. Governor of California, the federal court approved a class-wide settlement that required the state to reduce the number of people held in isolation by hundreds and to change conditions for those who remained. Implementation of that settlement faced challenges, and plaintiffs returned to court for further review and enforcement in 2019. In New York, settlement of the Annucci v. Peoples case meant the state agreed to reform policies governing how and for how long individuals were placed in solitary confinement; by 2019, plaintiff’s lawyers argued that implementation had not led to the required reductions and urged the legislature to enact the HALT Act. Other sources for changing numbers in solitary confinement include the facilities in prison and the dollar costs of confinement. Space, staff, and budgets have impacts that likely vary depending on the jurisdiction. Scholars have identified solitary confinement as a costly method of incarceration with yearly cost that “averages $75,000 per prisoner – about three times the average annual cost of incarceration in the United States.”

Since the 1930s, transnational rules have addressed incarceration; the League of Nations adopted its Standard Minimum Rules for the Treatment of Prisoners. Those rules recognized the use of isolation (“dark cells”). After World War II and the creation of the United Nations (U.N.), revised Standard Minimum Rules were issued in 1955 and formally adopted in 1977. Those rules were substantially revised and reissued on December 7, 2015, when the U.N.’s General Assembly adopted the revised United Nations Standard Minimum Rules for the Treatment of Prisoners, known as the Nelson Mandela Rules. The rules address an array of practices in prison including solitary confinement. The rules define prolonged solitary confinement as “solitary confinement for a time period in excess of 15 consecutive days” under Rule 44 and say that prolonged solitary confinement is impermissible under Rule 43. For solitary confinement fifteen days or less, the Rule 45 provides that it should be used “only in exceptional cases.” Specially, Rules 43 states:

  1. In no circumstances may restrictions or disciplinary sanctions amount to torture or other cruel, inhuman or degrading treatment or punishment. The following practices, in particular, shall be prohibited:
    1. Indefinite solitary confinement;
    2. Prolonged solitary confinement;
    3. Placement of a prisoner in a dark or constantly lit cell;
    4. Corporal punishment or the reduction of a prisoner’s diet or drinking water;
    5. Collective punishment.
  2. Instruments of restraint shall never be applied as a sanction for disciplinary offences.
  3. Disciplinary sanctions or restrictive measures shall not include the prohibition of family contact. The means of family contact may only be restricted for a limited time period and as strictly required for the maintenance of security and order.

Rule 44 states:

For the purpose of these rules, solitary confinement shall refer to the confinement of prisoners for 22 hours or more a day without meaningful human contact. Prolonged solitary confinement shall refer to solitary confinement for a time period in excess of 15 consecutive days.

And Rule 45 states:

  1. Solitary confinement shall be used only in exceptional cases as a last resort, for as short a time as possible and subject to independent review, and only pursuant to the authorization by a competent authority. It shall not be imposed by virtue of a prisoner’s sentence.
  2. The imposition of solitary confinement should be prohibited in the case of prisoners with mental or physical disabilities when their conditions would be exacerbated by such measures. The prohibition of the use of solitary confinement and similar measures in cases involving women and children, as referred to in other United Nations standards and norms in crime prevention and criminal justice, continues to apply

These rules interact with Articles 7 and 10 of the International Covenant on Civil and Political Rights (ICCPR). Article 7 states:

No one shall be subjected to torture or to cruel, inhuman or degrading treatment or punishment. In particular, no one shall be subjected without his free consent to medical or scientific experimentation.

Article 10 states:

  1. All persons deprived of their liberty shall be treated with humanity and with respect for the inherent dignity of the human person.
    1. Accused persons shall, save in exceptional circumstances, be segregated from convicted persons and shall be subject to separate treatment appropriate to their status as unconvicted persons;
    2. Accused juvenile persons shall be separated from adults and brought as speedily as possible for adjudication.
  3. The penitentiary system shall comprise treatment of prisoners the essential aim of which shall be their reformation and social rehabilitation. Juvenile offenders shall be segregated from adults and be accorded treatment appropriate to their age and legal status.

These documents reflect the sentiment in 1948 U.N.’s Declaration of Human Rights, whose opening states, “Whereas recognition of the inherent dignity and of the equal and inalienable rights of all members of the human family is the foundation of freedom, justice and peace in the world . . . .” In addition, the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (CAT) defines torture as “any act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person for such purposes as . . . punishing him for an act he. . . has committed or is suspected of having committed, or intimidating or coercing him . . . when such pain or suffering is inflicted by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity.” In 2011, the United Nations Special Rapporteur on Torture, Juan E. Méndez, concluded that, “Segregation, isolation, separation, cellular, lockdown, Supermax, the hole, Secure Housing Unit (SHU) . . . whatever the name, solitary confinement should be banned by States as a punishment or extortion technique.” Since, the Special Rapporteur on Torture has continued to conclude that prolonged solitary confinement can amount to torture and should be prohibited, including in 2013 and 2021. In some countries that apply international rules and guidance as domestic law, these human rights instruments can become binding obligations. In others, adherence may be voluntary. In 2017, the U.N. Office on Drugs and Crime issued “Assessing compliance with the Nelson Mandela Rules: A checklist for internal inspection mechanisms.” In 2022, the U.N. issued “Incorporating the Nelson Mandela Rules into National Prison Legislation: A Model Prison Act and Related Commentary.” U.N. provisions are a few of many resources. For example, the Committee of Ministers of the Council of Europe adopted a Recommendation in 2020, which updates the 2006 European Prison Rules. These rules address many facets of solitary confinement. Rule 60.6 states:

60.6.a Solitary confinement, that is the confinement of a prisoner for more than 22 hours a day without meaningful human contact, shall never be imposed on children, pregnant women, breastfeeding mothers or parents with infants in prison.

60.6.b The decision on solitary confinement shall take into account the current state of health of the prisoner concerned. Solitary confinement shall not be imposed on prisoners with mental or physical disabilities when their condition would be exacerbated by it. Where solitary confinement has been imposed, its execution shall be terminated or suspended if the prisoner’s mental or physical condition has deteriorated.

60.6.c Solitary confinement shall not be imposed as a disciplinary punishment, other than in exceptional cases and then for a specified period, which shall be as short as possible and shall never amount to torture or inhuman or degrading treatment or punishment.

60.6.d The maximum period for which solitary confinement may be imposed shall be set in national law.

60.6.e Where a punishment of solitary confinement is imposed for a new disciplinary offence on a prisoner who has already spent the maximum period in solitary confinement, such a punishment shall not be implemented without first allowing the prisoner to recover from the adverse effects of the previous period of solitary confinement. 60.6.f Prisoners who are in solitary confinement shall be visited daily, including by the director of the prison or by a member of staff acting on behalf of the director of the prison.

The European Court of Human Rights (ECtHR), which sits in Strasbourg, France, and many national courts cite the European rules as well as U.N. Conventions and the Nelson Mandela Rules. ECtHR has a website providing information on that court’s rulings on solitary confinement. For example, the ECtHR has concluded that the right to family life applies, including to people in solitary confinement. Öcalan v. Turkey (No. 2), European Court of Human Rights (Second Section) ECHR 286 (2014).

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Seeing Solitary is a tool that makes a decade of survey data accessible to those who want to learn more about solitary confinement in prisons in the United States. We hope that information will move you to take action, and that this website will be a starting point where you can:

  • Examine the data for the state where you live and learn more about what is currently happening in your jurisdiction.
  • Get in touch with local and/or national groups, including those listed on the Additional Resources page, to learn more about work in your area or how you can get projects started.
  • Read the information on this website and explore the links listed on the Research and Additional Resource pages.
  • Contact The Liman Center to ask questions or to request more information.