A/71/285 administrative status is illegal. 10 Administrative detention can only be justified if an individual presents a danger to the public or risks absconding when their presence is necessary in further proceedings. Such determinations must be done individually and be based on some kind of evidence. Any detention that does not respect such parameters is illegal. Furthermore, when detention becomes a routine measure of border enforcement, it may be, per se, arbitrary insofar as it is neither an exceptional measure of last resort, nor based upon a meaningful, individualized assessment of risk. 90. Additionally, there are human rights concerns relating to the impact of detention. Prolonged detention without a legal basis has been shown to have a devastating effect on the physical and mental health of migrants and asylum seekers, for example by contributing to post-traumatic stress disorder, anxiety and depression. This is frequently compounded by unacceptable conditions of detention, such as overcrowding, unsanitary toilet and shower facilities and unhygienic kitchens, as well as by scarce access to health care, family members, lawyers, international or civil society organizations, or physical and recreational activities. 91. Long periods of immigration detention can also lead to serious delays for migrants in claiming their economic and social rights, even after having been released. Research by the Office of the United Nations High Commis sioner for Refugees (UNHCR) suggests that detention disempowers migrants, who are often keen to work, owing to a sustained absence from the labour market and the emotional and mental toll of detention. 92. Of particular concern is the frequent presence of children in detention. Children are usually afforded additional protections by States and, according to many national policies, should not be detained. However, the Special Rapporteur has witnessed detained children in all the countries he has visited, so me of which have absurdly justified such detention by calling it protective custody. 93. When the age of the child is unknown, which is common when they are undocumented or coming from countries without robust birth registration systems, they are often detained until their age can be verified, which can take weeks or months. In some instances, while in detention, unaccompanied children live and sleep alongside adults, without any special accommodation made for their young age and without access to education. In others, families are separated in different sections of the detention facility according to age and gender. 94. The detention of children, even for short periods, can have severe psychological consequences. It has been made clear by the Committee on the Rights of the Child and reinforced by other human rights mechanisms that immigration detention can never, ever, be in the best interest of a child and that the immigration detention of children, whether unaccompanied or together with their families, constitutes a violation of child rights. Consequently, both unaccompanied children and families with children should always benefit from alternatives to detention. __________________ 10 18/24 CMW/C/GC/2, para. 2; Inter-American Court of Human Rights, Vélez Loor v. Panama, para. 171; Inter-American Court of Human Rights, Pacheco Tineo v. Bolivia, para. 131; and Court of Justice of the European Union, Sélina Affum v. Préfet du Pas-de-Calais. 16-13509