<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (January 2013) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (January 2013) (Learn how and when to remove this template message) </Td> </Tr> <P> Supermax (short for: super-maximum security) is a primarily U.S. English term used to describe "control - unit" prisons, or units within prisons, which represent the most secure levels of custody in the prison systems of certain countries . The objective is to provide long - term, segregated housing for inmates classified as the highest security risks in the prison system--the "worst of the worst" criminals--and those who pose a threat to both national and global security . </P> <P> According to the National Institute of Corrections, an agency of the United States government, "A supermax is a stand - alone unit or part of another facility and is designated for violent or disruptive inmates . It typically involves up to 23 - hour - per - day, single - cell confinement for an indefinite period of time . Inmates in supermax housing have minimal contact with staff and other inmates," a definition confirmed by a majority of prison wardens . </P>

What is the main purpose of the supermax prison ​