Segregation, also referred to as solitary confinement or restricted housing, is a practice widely used in prisons and jails in the United States today, largely as a means to fulfill a corrections department's top priority: the safety of its staff and the incarcerated people under its care. Incarcerated people are placed into segregation for a variety of reasons, including but not limited to breaking the rules of an institution, violent or disruptive behavior, or as a preventive measure for people who have been deemed a risk to the safety and security of a facility. Segregation can also be used to protect those at high risk of sexual assault and/or physical abuse in the general population or to hold people in a temporary confinement setting to await a disciplinary hearing or an investigation to be completed. 
Many prisons and jails have various forms of segregated housing, but different jurisdictions often use different terms to describe this housing, for example, restricted housing, isolation, disciplinary segregation, and special or intensive management.
The terms in most frequent use today include:
> Disciplinary (or punitive) segregation: This form of housing is used to sanction incarcerated people for violating facility rules. As in the larger criminal justice process, generally charges are written, a hearing is held, evidence is presented, and, if the accused is found guilty, a term in segregated housing may be imposed.
> Administrative segregation: This form of housing is typically used to remove incarcerated people from the general prison or jail population if they are thought to pose a risk to the safety and security of an institution. It is not used as a direct response to a rule violation, but as a preventive measure.
> Protective custody: A form of housing used to remove incarcerated people— such as those who are mentally ill, intellectually or developmentally disabled, lesbian, gay, bisexual, transgender, intersex, gender nonconforming, or former law enforcement officers—from a facility's general population when they are thought to be at risk of harm, abuse, or victimization. Other reasons for risk include a history of being victimized, physical limitations, or the nature of the committing offense. While some people who fear for their safety in the general population may request protective custody, this status can also be conferred involuntarily. Many times people in protective custody are housed in administrative segregation, with the same level of restrictions on out-of-cell time, privelages, and services.
The conditions in segregated housing can vary depending on the type of segregation and the jurisdiction, or even the particular facility where an individual is being held. Yet whatever the label, the experience for the person is generally the same—confinement in a small, isolated cell (alone, or sometimes with a cellmate) for an average of 23 hours a day with limited human interaction (with staff or sometimes other inmates in adjoining cells), privileges, access to services, and programming, and in an environment that ensures maximum control over the individual. 
There are indications that the use of segregated housing has grown substantially in recent years, yet the precise number of people held in segregation on any given day is not known with certainty. According to a survey conducted by the U.S. Department of Justice, Bureau of Justice Statistics, the number of people in restricted housing units in prisons and jails nationwide increased from 57,591 in 1995 to 81,622 in 2005—an almost 42 percent increase.  This is the most recent national data available; however, providing an accurate count of people in segregation is methodologically challenging and these challenges could have led to an under-representation of the number of people in segregation.
Based on research conducted by Vera and others over the past five years, the percentage of a state prison system's daily population that is held in segregated housing ranges from five to 14 percent. In the federal system, recent research found that the Federal Bureau of Prisons—the largest prison system within the United States—held five percent of its prisoners in segregated housing units in November 2013.  These numbers are snapshots of the number of people held in segregation on a given day. When considering the number of people who will spend some time in segregation throughout their period of custody, the number is much higher. For example, Vera's analysis of administrative data from one state found that, while five percent of the population was in segregated housing at any given time, 60 percent of prisoners had been in segregated housing at some point during their current sentence and 25 percent had spent time in segregation during the previous year.
Decades of research suggest that the common characteristics of segregation—social isolation, reduced environmental stimulation, and loss of control over all aspects of daily life—can produce negative impacts on people housed there, including hypersensitivity to stimuli; distortions and hallucinations; increased anxiety and nervousness; diminished impulse control; severe and chronic depression; appetite loss and weight loss; heart palpitations; talking to oneself; problems sleeping; nightmares; self-mutilation; difficulties with thinking, concentration, and memory; and lower levels of brain function, including a decline in electroencephalogram (EEG) activity after only seven days in segregation.  When a person is released from segregated housing, these psychological effects may have the potential to undermine a person's ability to adjust back into a prison's general population or the community to which he or she returns. In addition, there may be negative impacts on staff that work on these units as well, but this is based mostly on anecdotal information as there is currently little research in this area. 
The most widely accepted and cited reason among corrections officials for using segregated housing is to ensure safety, order, and control within a prison. Many believe that segregated housing helps restrain the amount and seriousness of violence within facilities and that a decrease in its use would endanger both incarcerated people and staff.  However, there is extensive evidence that counters the belief that segregated housing increases facility safety.  One study, for example, found no relationship between the opening of "supermax" prisons and the aggregate levels of prisoner-on-prisoner assaults in three prison systems (Illinois, Arizona, and Minnesota).  Colorado has decreased its use of segregated housing by 85 percent, and prisoner-on-staff assaults are the lowest they have been since 2006. [100 Other states—such as Illinois, Maine, New Mexico, and Washington—have also reduced their use of segregated housing and increased the use of alternative strategies.  Although it is too soon to fully assess outcomes in these states, evidence to date suggests there has been little or no increase in violence. 
Other empirical and anecdotal evidence suggests that segregated housing may have little influence on improving the behavior of incarcerated people. Studies have contrasted "control-oriented" prisons, which rely on formal sanctions like segregation, with others that are "responsibility-based"—which provide incarcerated people with self-governance opportunities—or "consensual," which incorporate features of both the control-oriented and responsibility-based models of prison management. Researchers tested the relationship between these approaches and prison order and found that prisons that employed a responsibility-based or consensual management model experienced lower levels of minor and serious disorder than prisons that were more control-oriented.  Moreover, there is no evidence that confinement in a supermax facility produces a deterrent effect on the individual.  A recent study found that exposure to short-term disciplinary segregation as a punishment for initial violence did not deter incarcerated people from committing further violence in prison.  Some theoretical models describe the behavior of incarcerated people as a reaction to the strains, frustrations, and pains of imprisonment combined with little access to mitigating factors.
Recent years have seen a growing interest among corrections officials and policy makers at the local, state, and federal level to decrease the use of segregated housing in the nation's prisons and jails. This is, in part, due to the shift in public opinion and increased understanding of the potentially negative effects of isolation. A subcommittee of the U.S. Senate Judiciary Committee held hearings in 2012 and 2014 focused on reassessing the use of solitary confinement.  In 2014, 10 states announced or implemented policy changes to reduce the number of adults or juveniles held in segregated housing, improve the conditions in segregation units, or facilitate the return of segregated people to a prison's general population.  Some, like Colorado, passed legislation limiting people with serious mental illnesses from being housed in long-term segregation.  And, most recently, New York City's Department of Correction made the decision to ban the use of segregated housing for all those in its custody 21 years old and younger. 
Yes. A common objection among corrections staff to reducing the use of segregation is that few safe alternatives exist and those that do are too costly to implement. However, in the past decade, several jurisdictions—including some that Vera has worked with—have successfully reduced their use of segregated housing and implemented safe alternatives. The changes have decreased their reliance on segregation while still keeping staff and inmates safe.
For example, rather than rely on segregated housing to deter misbehavior, some prison systems are providing incarcerated people who are most likely to misbehave with special programming. Washington has an Intensive Transition Program for incarcerated people with chronic behavior problems who are frequently placed in segregated housing, in which they move through a curriculum in stages, progressively learning self-control and gradually engaging in opportunities to socialize until they are ready to return to the prison's general population.  Pennsylvania is in the process of implementing Behavior Modification Units with a similar focus.  Pennsylvania, Washington, and New Mexico have all created step-down programs for gang members held in segregated housing.
Vera's Safe Alternatives to Segregation Initiative aims to address this need by partnering with five corrections systems to find ways to significantly reduce their reliance on segregated housing through the advancement of safe and effective alternatives. These alternatives can include implementing a structured sanctions grid to ensure appropriate and proportionate responses are utilized and using alternative responses to less serious rule violations, such as mediation or anger management classes, withholding access to the commissary, removing TV privileges, restricting visitation rights, making the prisoner responsible for the costs of damaged property, and assigning the prisoner to an undesirable work shift.
For those who need protective custody, housing that has the same privileges and services as the general population can be provided. In addition, officials can provide opportunities for programming and congregate activity in disciplinary and administrative segregation. All of these options increase the likelihood of successful reintegration back into the general population.
The Safe Alternatives to Segregation Resource Center contains many resources on segregated housing of various types, from academic journal articles on the effects of solitary confinement to practical tools that can help corrections professionals reform their use of segregation. The resource center is searchable by keyword, and it also groups resources into major topics in the field, such as "juveniles in segregation" or "segregation and mental health."
 In 2012, the U.S. Department of Justice finalized the National Standards to Prevent, Detect, and Respond to Prison Rape. The standards include specific provisions designed to protect vulnerable populations from sexual abuse and sexual harassment in confinement. See: http://www.gpo.gov/fdsys/pkg/FR-2012-06-20/pdf/2012-12427.pdf.
 Association of State Correctional Administrators and Liman Program, Yale Law School, Time-In-Cell: The ASCA-Liman 2014 National Survey of Administrative Segregation in Prison (August 2015).
 Percent increase calculation done by Vera researchers as part of its Segregation Reduction Project, based on data from the 1995 and 2005 Census of State and Federal Adult Correctional Facilities. For an estimate of the number of people in segregated housing in 1995, see U.S. Department of Justice, Bureau of Justice Statistics, Census of State and Federal Adult Correctional Facilities, 1995 [Computer file]. Conducted by the U.S. Department of Commerce, Bureau of the Census. ICPSR ed. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [producer and distributor], 1998. Doi:10.3886/ICPSR06953.v1. For an estimate of the number of people in segregated housing in 2005, see U.S. Department of Justice, Office of Justice Programs, Bureau of Justice Statistics, Census of State and Federal Adult Correctional Facilities, 2005. ICPSR24642-v2. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2010-10-05. http://doi.org/10.3886/ICPSR24642. v2.
 In 2002, 40 states responded to a National Institute of Corrections survey with respondents having an average of five percent of prisoners in administrative and disciplinary custody. See James Austin and Kenneth McGinnis, Classification of High-Risk and Special Management Prisoners: A National Assessment of Current Practices (Washington, DC: U.S. Department of Justice, National Institute of Corrections, 2004), 29-30, https://s3.amazonaws.com/static.nicic.gov/Library/019468. pdf.
 Sharon Shalev, A Sourcebook on Solitary Confinement (London: Mannheim Centre for Criminology, London School of Economics, 2008). For information on negative effects of solitary confinement, see Haney, 2003, 130-136; Paul Gendreau, et al., "Changes in EEG Alpha Frequency and Evoked Response Latency During Solitary Confinement," Journal of Abnormal Psychology 79 (1972), 57-58; Stuart Grassian, "Psychiatric Effects of Solitary Confinement," Washington University Journal of Law & Policy, 22 (January 2006): 325-383; Stuart Grassian, "Psychopathological Effects of Solitary Confinement," American Journal of Psychiatry 140, no.11 (1983): 1450-1454.
 See Craig Haney and Mona Lynch, "Regulating Prisons of the Future: A Psychological Analysis of Supermax and Solitary Confinement," New York University Review of Law and Social Change 23 (1997): 568.
 See Mears, 2006, p. 41; Chad S. Briggs, Jody L. Sundt, and Thomas C. Castellano, "The Effect of Supermaximum Security Prisons on Aggregate Levels of Institutional Violence," Criminology 41, no. 4 (2003): 1342. The physical conditions of a prison—some of which are present in segregated housing units—have been found to relate to misconduct, with worse levels of noise, clutter, dilapidation, and lack of privacy predicting higher levels of violence. See D.M. Bierie, "Is Tougher Better? The Impact of Physical Prison Conditions on Inmate Violence," International Journal of Offender Therapy and Comparative Criminology 56, no. 3 (2012): 338-355.
 There are few, if any, credible studies on the impact of administrative segregation on facility safety; see Daniel P. Mears, "Supermax Prisons: The Policy and the Evidence," Criminology & Public Policy 12, no. 4 (2013): 681-720. The authors of a report on the use of segregated housing in federal prisons said that the literature does not make it "clear if there is a causal relationship between segregation policies and institutional safety," see CNA, 2014. Moreover, the Federal Bureau of Prisons has never assessed whether the use of segregated housing has any effect on prison safety; see U.S. Government Accountability Office (GAO), 2013, p. 33.
 Briggs, Sundt, and Castellano, 2003, p. 1367.
 In October 2009, Colorado Department of Corrections housed 1,166 incarcerated people in long-term administrative segregation. In April 2014, 215 incarcerated people were housed in long-term administrative segregation. Office of Planning and Analysis Prison Operations, Colorado Department of Corrections (CDOC), SB 11-176 Annual Report: Administrative Segregation For Colorado Inmates (Colorado: CDOC, 2015), 3; Rick Raemisch, director, Colorado Department of Corrections, e-mail exchange with Vera, Washington, DC, February 27, 2015.
 Colorado, Kansas, Maine, Mississippi, and Ohio greatly reduced their use of segregated housing and officials reported little or no adverse impact on facility safety; see U.S. Government Accountability Office (GAO), 2013, 34. Washington has reduced the number of prisoners assigned to maximum custody by 47 percent from January 2011 to December 2014; see Bernie Warner, secretary, Washington Department of Corrections, e-mail exchange with Vera, Washington, DC, March 12, 2015; Gregg Marcantel, secretary, New Mexico Corrections Department, e-mail exchange with Vera, Washington, DC, March 25, 2015.
 When Maine cut its population in segregated housing, incidents of prison violence dropped. See American Civil Liberties Union of Maine, 2013, pp. 30-31.
 John J. DiIulio, Governing Prisons: A Comparative Study of Correctional Management (New York: Free Press, 1987); and Michael D. Reisig, "Rates of Disorder in Higher-Custody State Prisons: A Comparative Analysis of Managerial Practices," Crime and Delinquency 44, no. 2 (1998), 230, 239.
 Chad S. Briggs, Jody L. Sundt, and Thomas C. Castellano, 2003, p. 1370.
 Robert G. Morris, "Exploring the Effect of Exposure to Short-Term Solitary Confinement Among Violent Prison Inmates," Journal of Quantitative Criminology DOI 10.1007/s10940-015-9250-0 (2015): 1-24.
 United States Senate Committee on the Judiciary, Subcommittee on the Constitution, Civil Rights and Human Rights, "Reassessing Solitary Confinement: The Human Rights, Fiscal, and Public Safety Consequences," June 19, 2012, http://www.judiciary.senate.gov/imo/ media/doc/CHRG-112shrg87630.pdf; United States Senate Committee on the Judiciary, Subcommittee on the Constitution, Civil Rights, and Consequences, "Reassessing Solitary Confinement II: The Human Rights, Fiscal, and Public Safety Consequences," February 25, 2014, http://www. judiciary.senate.gov/meetings/reassessing-solitary-confinement-ii-the-human-rights-fiscal-and-public-safety-consequences.
 Eli Hager and Gerald Rich, "Shifting Away from Solitary," The Marshall Project, December 23, 2014. Also, South Dakota repealed a law that allowed a county prisoner to be kept in solitary confinement on bread and water for refusal to labor or obey necessary orders, see 2014 S.D. Laws 118 repealed S.D. Codified Laws § 24-11-34 (2014).
 "The department shall not place a person with serious mental illness in long-term isolated confinement except when exigent circumstances are present," Colorado Revised Statute, 17-1-113.8 (2014).
 In September 2014, the New York City Department of Correction ordered the end of solitary confinement for 16- and 17-year-olds by the end of the year. See Michael Shwirtz, "Solitary Confinement to End for Youngest at Rikers Island," New York Times, September 28, 2014. In January 2015, the New York City Board of Correction adopted rules relating to enhanced supervision housing and punitive segregation, which stated that sufficient resources are made available for staffing and implementing necessary alternative programming; as of January 1, 2016, inmates ages 18 through 21 will no longer be placed in enhanced supervision housing. Rules of the City of New York, Chapter 1, Title 40, §1-16 (c)(1)(ii).
 Carlyne Kujath, manager, Strategic Operations, Washington Department of Corrections, e-mail exchange with Vera, Washington, DC, April 15, 2015.
 See Shirley Moore Smeal, executive deputy secretary, Pennsylvania Department of Corrections, e-mail exchange with Vera, Washington, DC, April 10, 2015.