A/HRC/37/50 Moreover, experience shows that any form of arbitrary detention exposes migrants to increased risks of torture and ill-treatment. 27. The Human Rights Committee has repeatedly considered that "the combination of the arbitrary character of the [...] detention, its protracted and/or indefinite duration, the refusal to provide information and procedural rights to the [detainees] and the difficult conditions of detention are cumulatively inflicting serious psychological harm upon them, and constitute treatment contrary to article 7 of the Covenant."44 Indeed, the experience of being subjected to detention that is neither necessary nor proportionate to serve any legitimate purpose, particularly in conjunction with its prolonged and potentially indefinite duration, and with the absence of any effective legal remedy has been shown to add significant mental and emotional stress to the already extremely vulnerable situation of irregular migrants, with many cases reported of self-harm, post-traumatic stress disorder, anxiety and depression. Thus, even factors that may not necessarily amount to ill-treatment when applied as an isolated measure and for a very limited period of time - such as unjustified detention, delayed access to procedural rights, or moderate physical discomfort - can cross the relevant threshold if applied cumulatively and/or for a prolonged or open-ended period of time. 28. In the view of the Special Rapporteur, as a general rule, the longer a situation of arbitrary detention and inadequate conditions lasts, and the less affected detainees can do to influence their own situation, the more intense their mental and emotional suffering will become, and the higher is the likelihood that the prohibition of ill-treatment has been breached. Depending on the circumstances, this threshold can be reached very quickly, if not immediately, for migrants in situations of increased vulnerability, such as children, women, older people, persons with disabilities, medical conditions, or torture trauma, and members of ethnic or social minorities including lesbian, gay, bisexual, transgender and intersex (LGBTI) persons. In particular, the Special Rapporteur endorses and reiterates the view expressed by his predecessor that the deprivation of liberty of migrant children based solely on their own or their parents’ migration status is never in the best interests of the child, exceeds the requirement of necessity, is grossly disproportionate and, even in case of short term detention, may amount to cruel, inhuman or degrading treatment.45 29. In the view of the Special Rapporteur, detention based solely on migration-status, as such, can also amount to torture, most notably where it is being intentionally imposed or perpetuated for purposes such as deterring, intimidating, or punishing irregular migrants or their families, coercing them into withdrawing their requests for asylum, subsidiary protection or other stay, agreeing to voluntary repatriation, providing information or fingerprints, or with a view to extorting money or sexual acts, or for reasons based on discrimination of any kind, including discrimination based on immigration status.46 D. Smuggling and Trafficking of Migrants 30. Much could be said about the often harsh and strenuous living conditions millions of migrants are exposed to in transit and destination States throughout the world, especially those finding themselves in irregular situations. The difficulties and threats experienced by this particularly vulnerable and underprivileged population group may range from discriminatory laws, administrative obstruction and inadequate access to public services and resources, to corruption, threats, violence or indifference on the part of State officials, and from harassment and aggression on the part of the local population to systematic abuse and exploitation by criminal groups, often even in collusion with State officials. For the present purposes, two areas of particularly tragic practical relevance for the prohibition of torture and ill-treatment shall be explored, namely torture and ill-treatment occurring in connection with 44 45 46 CCPR, F.J. et al._v._Australia_(No.2233/2013, 22.03.2016), §10.6; CCPR, F.K.A.G._et_al._v._Australia_(No.2094/2011, 26.07.2013), §9.8; CCPR, M.M.M._et_al. _v._Australia_(No.2136/2012,_25.07.2013), §10.7. A/HRC/28/68(05.03.2015), §80; ECtHR, S.F._et_al._v._Bulgaria_(No.8138/16), 07.12.2017. See also: CAT, GC_No.4_(2017)_Art.3, §14. 9