The design of the prison is closely linked to its regime. Together they have great impact on prisoners’ experience of the prison and their wellbeing. The section which follows examines international standards regarding prison conditions and regime, with a special emphasis on solitary confinement units. 4.2 I nternational standards regarding prison conditions and regime Human rights instruments form the guiding principles and minimum standards for the humane treatment of prisoners. The daily running of prisons is governed by national laws and prison rules which include detailed practical provisions, but they must in all cases conform to the overarching international human rights standards ensuring that prisoners are held in a humane manner in a sanitary and healthy environment. Indeed, monitoring bodies and the courts pay particular attention to the physical conditions in which prisoners are held and will be more inclined to find a violation of human rights law where these fall below the required minimum standards. Having regard to the diversity in resources, laws and cultures of states, Article 2 of the UN Standard Minimum Rules (SMR) stipulates that standards should “serve to stimulate a constant endeavour to overcome practical difficulties in the way of their application, in the knowledge that they represent, as a whole, the minimum conditions which are accepted as suitable by the United Nations”. In its General Comment 21, on the interpretation of what is meant by treating all persons deprived of liberty with “humanity and with respect for their inherent dignity” (ICCPR, Article 10), the UN Human Rights Committee made clear that such treatment is fundamental, and “cannot be dependent on the material resources available in the State party” (Human Rights Committee General Comment 21, Article 10 of the International Covenant on Civil and Political Rights (44th Session 1992)). In other words, these minimum requirements must be observed, “even if economic or budgetary considerations may make compliance with these obligations difficult”56. As their title implies, the Standard Minimum Rules (and other similar instruments) set out the baselevel minimum requirements for the operation of prisons globally. The standards examined below are generic and apply to all prisons and to all sections of the prison, but they take on a particular importance in solitary confinement units. Conditions which fall below these minimum standards may constitute cruel, inhuman or degrading treatment or punishment. Adherence to, or even improvement on, the standards discussed below still does not mean that solitary confinement necessarily becomes any less damaging. But ensuring humane conditions and access to meaningful human contact may help mitigate some of its harmful effects. A. Physical conditions As noted above, instruments such as the UN Standard Minimum Rules (SMR) and European Prison Rules (EPR) prescribe minimum standards of physical conditions in all places of confinement. These include: 40 Sourcebook on solitary confinement: Design, physical conditions and regime in solitary confinement units