6ROLWDU\FRQILQHPHQWRISULVRQHUV 6ROLWDU\FRQILQHPHQWRISULVRQHUV ,QWURGXFWLRQ 53. Solitary confinement of prisoners is found, in some shape or form, in every prison system. The CPT has always paid particular attention to prisoners undergoing solitary confinement, because it can have an extremely damaging effect on the mental, somatic and social health of those concerned.9 This damaging effect can be immediate and increases the longer the measure lasts and the more indeterminate it is. The most significant indicator of the damage which solitary confinement can inflict is the considerably higher rate of suicide among prisoners subjected to it than that among the general prison population. Clearly, therefore, solitary confinement on its own potentially raises issues in relation to the prohibition of torture and inhuman or degrading treatment or punishment. In addition, it can create an opportunity for deliberate ill-treatment of prisoners, away from the attention of other prisoners and staff. Accordingly, it is central to the concerns of the CPT and, on each visit, delegations make a point of interviewing prisoners in solitary confinement in order to examine their conditions of detention and treatment and to check the procedures for deciding on such placements and reviewing them. In this section of its General Report, the CPT sets out the criteria it uses when assessing solitary confinement. The Committee believes that if these criteria are followed, it should be possible to reduce resort to solitary confinement to an absolute minimum, to ensure that when it is used it is for the shortest necessary period of time, to make each of the solitary confinement regimes as positive as possible, and to guarantee that procedures are in place to render the use of this measure fully accountable. 9. The research evidence for this is well summarised in Sharon Shalev’s “A Sourcebook on Solitary Confinement” (Mannheim Centre for Criminology, London, 2008), available electronically at www.solitaryconfinement.org