Maximum security was applied to especially dangerous recidivists and exonerated capital convicts. Especially dangerous recidivists could include political prisoners who have already been incarcerated. Unlike other security levels, maximum security provided for 24/7 lockdown.
In 1961 through 1980, ‘supermax’ prisoners of state were kept in the Mordovian maximum-security camp.
The maximum-security area in Perm-36 camp was peculiarly cruel. Most of its prisoners were dissidents who were convicted of anti-Soviet agitation and propaganda for the second or even the third time. They were kept in small two/three/four-man cells. Each cell population worked in working cells of the same size, in the same hut. Prisoners from different cells could never meet each other, even when walking from living cells to working ones. They saw nobody but there cellmates and guards for years.
Latticed windows of the cells were blocked from outside by blank blinds, outbuildings or fences. Small iron-clad exercise yards with concrete floors and barbed-wire mesh overhead were used for open-air time. The prisoners could see nothing but the sky outside the windows and the fences for years. Even grass which pierced out through concrete floor cracks was weeded away thoroughly by the guard.
Beside dissidents, this division accommodated exonerated capital convicts who were charged with World-War-II collaboration. They were kept in six-man cells for two-thirds of the term, then switched over to cell-free treatment and engaged in area maintenance.