2.2 Human rights risk area 2: The prison regime Classification and categorization will inform the allocation and security regimes and, in some cases, the security measures within such regimes applied to (suspected) violent extremist prisoners. Security measures and related restrictions must be imposed on prisoners only on the basis of the results of objective assessments and in accordance with the principles of necessity and proportionality, in particular to ensure their safe custody. As already highlighted, inadequate detention conditions and (disproportionately) 231 harsh security measures can increase the risk of radicalization to terrorism or violence. Assigning prisoners an unnecessarily high security level can also compromise rehabilitation prospects, as this usually has an impact on prisoners’ contacts with their families, their participation in rehabilitation programmes, the amount of time they spend outside their 232 cells, and so on. There is an ongoing debate about the most appropriate way to house (suspected) violent extremist prisoners, and different options have been considered across the OSCE 233 region. One approach is to separate these prisoners from the general prison population (separation), whether this means they are held in isolation from each other (isolation), together in one place (concentration) or dispersed across a small number of facilities that are most often high-security wings within regular prisons (dispersal). Another approach is to integrate them with the general prison population (integration). Some OSCE participating States have also adopted a mix of these approaches. Separation may prevent the violent radicalization and recruitment of other prisoners, facilitate the implementation of targeted interventions, and reduce the number of staff requiring specialized training. On the other hand, concentration may enable the maintenance or re-creation of the operational command structure of certain violent extremist or terrorist groups, facilitate the sharing of information and operational skills between prisoners, and increase the risk of prison violence and illegal activities. It may cause feelings of stigmatization and mistrust or be perceived by other prisoners and the separated group as a sign of raised status or authority. While dispersal may reduce such feelings, it may be less effective in preventing the violent radicalization and recruitment of other prisoners. Isolation is highly problematic if it results in prisoners being kept in solitary confinement, which, in many cases, will amount to torture and other ill-treatment. Separation may also prevent prisoners from exposure to alternative viewpoints and affect their participation in rehabilitation programmes. Integration may, on the other hand, expose prisoners to alternative perspectives, which can support disengagement efforts. Integration does not, however, address the risks of 231 Report to the Government of the Netherlands on the Visit to the Netherlands Carried Out by the European Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment (CPT) from 2 to 13 May 2016, CPT/Inf (2017) 1, para. 50. 232 ODIHR & PRI, Guidance Document on the Nelson Mandela Rules, op. cit., note 10, Chapter 1, para.71. 233 See section 2.1 on classification, risk and needs assessments. Different organizations use different terms to distinguish between placement regimes. RAN refers to concentration and dispersal regimes: EU-RAN, “Approaches to Countering Radicalization and Dealing with Violent Extremist and Terrorist Offenders in Prisons and Probation”, op. cit., note 80, p. 21. 54