Although first implemented in the late 1700s as a measure of criminal justice reform, contemporary prison segregation is an increasingly popular, yet contentious, correctional practice aimed at containing difficult-to-manage behavior that threatens institutional safety and management. High-security housing blocks designed to separate at-risk and problematic inmates from the general prison population are referred to by a variety of names depending on the institution, including administrative segregation (AS; ad-seg), special housing units (the shoe), special management, and restrictive housing. Although less-often used in an official capacity, segregation is also commonly described as solitary confinement or the hole.

Despite the interchangeable use of these labels, there are two general types of segregation used in most U.S. correctional facilities: disciplinary segregation (DS) and AS. DS typically refers to the ...