Control units, Supermax prisons, and devices of torture
Isolation and lockdown (confining prisoners to their cells for 23 to 24 hours a day) have traditionally been used as temporary measures, to punish individual prisoners or control the prison environment.
However, as these forms of incarceration have grown increasingly common, isolation has become a permanent condition for more and more prisoners. Along with the multiplication of control units, prisoners and their advocates have also begun to report increasingly routine use of devices like stun belts, stun guns, or restraint chairs.
Written in 2003, "The prison inside the prison" looks at the use of solitary confinement in U.S. prisons.