189. Where there is a structural deprivation of detainees’ basic rights, such as access to “food, water, clothing, health care and a minimum of space, hygiene, privacy and security,” conditions of detention may also constitute cruel, inhuman or degrading treatment or punishment.301 The “combined deprivation and the non-fulfilment of these existential rights” would not only violate detainees’ right to be treated with humanity and respect for their dignity, but could also cause severe psychological or physical pain or suffering and thereby amount to ill-treatment.302 Furthermore, the use of force, restraint techniques or other instruments to control a detainee may also constitute torture or ill-treatment when they are disproportionate and/or applied in a degrading and painful manner.303 The Special Rapporteur on torture and the Committee against Torture have both condemned the use of restraint chairs, since these are “inherently inhuman, degrading or painful”.304 Moreover, the use of restraints to punish detainees can never be justified.305 190. Solitary confinement306 is also an important cause of concern. When isolation is prolonged, it can constitute torture or ill-treatment, depending on the circumstances of a particular case.307 The determining circumstances include the purpose of the confinement, the conditions, the duration, the effects on the detainee in question, as well as the particular vulnerability of that detainee.308 Solitary confinement is never acceptable when it is imposed as a technique to extract information or a confession.309 It also amounts to torture or ill-treatment when it is used to punish detainees for breaching prison discipline, if it causes them to experience severe pain or suffering.310 It should always remain a last resort, <http://hudoc.echr.coe.int/sites/eng/pages/search.aspx?i=001-57506>; ECtHR, Aksoy v. Turkey, Application No. 21987/93, 18 December 1996, <http://hudoc.echr.coe.int/sites/eng/pages/search.aspx?i=001-58003>; ECtHR, El-Masri v. the former Yugoslav Republic of Macedonia, Application No. 39630/09, 13 December 2012, <http://hudoc.echr.coe.int/sites/eng/pages/search.aspx?i=001-115621>. 301 UN Special Rapporteur on torture, “Study on the phenomena of torture”, op. cit., note 283, para. 230. 302 UN Special Rapporteur on torture, “Study on the phenomena of torture”, ibid.; “Statement of the UN Special Rapporteur on torture at the Expert Meeting on the situation of detainees held at the U.S. Naval Base at Guantanamo Bay – Inter-American Commission on Human Rights”, OHCHR website, op. cit., note 108. 303 UN Special Rapporteur on torture, Theo van Boven, Report to the Commission on Human Rights, E/CN.4/2004/56, 23 December 2003, paras. 44-45, <http://ap.ohchr.org/documents/alldocs.aspx?doc_id=9140>. 304 UN Special Rapporteur on torture, Juan Mendez, Interim report to the General Assembly, 9 August 2013, A/68/295, para. 58, <http://www.un.org/Docs/journal/asp/ws.asp?m=A/68/295>. See, also, UN CAT, Report of the Committee against Torture, Twenty third session, Twenty fourth session, A/55/44, para. 180(c), <http://www.un.org/ga/search/view_doc.asp?symbol=A/55/44&referer=/english/&Lang=E>. 305 UN Special Rapporteur on torture, Report to the Commission on Human Rights, E/CN.4/2004/56, op. cit., note 303, para. 45. See, also, “Standard Minimum Rules for the Treatment of Prisoners”, op. cit., note 280, Rule 33. 306 For the purpose of this report, solitary confinement is defined as the “physical isolation of individuals who are confined to their cells for 22 to 24 hours a day. (…) Meaningful contact with other people is typically reduced to a minimum. The reduction in stimuli is not only quantitative but also qualitative.” “The Istanbul Statement on the Use and Effects of Solitary Confinement”, 9 December 2007, p. 1, <http://solitaryconfinement.org/uploads/Istanbul_expert_statement_on_sc.pdf>; UN Special Rapporteur on torture, Juan Mendez, Interim report to the General Assembly, A/66/268, 5 August 2011, para. 25, <http://www.un.org/Docs/journal/asp/ws.asp?m=A/66/268>. 307 UN HRC, General Comment No. 20, op. cit., note 282, para. 6; UN Special Rapporteur on torture, Interim report to the General Assembly, A/66/268, ibid., para. 76; UN Special Rapporteur on torture, Manfred Nowak, Interim report to the General Assembly, A/63/175, 28 July 2008, para. 80, <http://www.un.org/Docs/journal/asp/ws.asp?m=A/63/175>. The UN Special Rapporteur on torture defined “prolonged solitary confinement” as a period exceeding 15 consecutive days, “because at that point, (…) some of the harmful psychological effects of isolation can become irreversible”. While this indication provides useful guidance, ODIHR also shares the view of the Special Rapporteur that such time period remains of an arbitrary nature as the adverse impact of solitary confinement depends greatly on the individual’s personal circumstances. UN Special Rapporteur on torture, Interim report to the General Assembly, A/66/268, ibid., para. 26. 308 Ibid., para. 71. 309 Ibid., para. 73. 310 Ibid., para. 72. 79