36 156 mental health. While deprivations of liberty may be permissible in such situations, the Commission has emphasized that any detention of this kind must be based on established domestic and international law and must be done on the grounds and according to the procedures prescribed in the Constitution or other law and must be demonstrably necessary, fair and not arbitrary. Detention in such circumstances must also be subject to prompt judicial oversight and, when the State justifies continued detention, must be subject to judicial oversight at reasonable 157 intervals. 169. In that regard, the Commission has elaborated upon the principle whereby immigration detention is to be the exception. It wrote that immigration policy must be premised on a presumption of liberty and not on a presumption of detention. Immigration detention is to be the exception and justified 158 by the State as lawful and non- arbitrary. 170. Similarly, the Court held that immigration detention should never have a punitive end and wrote the following: In a democratic society punitive power is exercised only to the extent that is strictly necessary in order to protect fundamental legal rights from serious attacks that may impair or endanger them. The opposite would result in the abusive exercise of the punitive power of the State. Similarly, the Working Group on Arbitrary Detention sustained that right to personal liberty “requires that States should have recourse to deprivation of liberty only insofar as it is necessary to meet a pressing 159 societal need, and in a manner proportionate to that need.” 171. As the Court has held, in order for a deprivation of liberty for immigration-related reasons not to be arbitrary, the detention must be done in accordance with the law, for a legitimate end and be suitable, necessary and proportional. Elaborating, the Court wrote the following: without prejudice to the lawfulness of the detention, it is necessary to assess, in each case, the compatibility of the legislation with the Convention, understanding that such law and its application must respect the requirements listed below, in order to ensure that this measure is not arbitrary: i) that the purpose of the measures that deprive or restrict liberty is compatible with the Convention; ii) that the measures adopted are appropriate to achieve the sought-after purpose; iii) that they are necessary, in the sense that they are absolutely essential to achieve the purpose sought and that, among all possible measures, there is no less burdensome one in relation to the right involved, that would be as suitable to achieve the proposed objective. Hence, the Court has indicated that the right to personal liberty supposes that any limitation of this right must be exceptional; and, iv) that the measures are strictly proportionate, so that the sacrifice inherent in the restriction of the right to liberty is not exaggerated or excessive compared to the advantages obtained from this restriction and the achievement of the purpose sought. Any restriction of liberty that is not based on a justification that will allow an assessment of whether it is adapted to the conditions set out above 160 will be arbitrary and will thus violate Article 7(3) of the Convention. 172. On the subject of collective detentions, the Court has held that 156 IACHR, Report No. 51/01 (Admissibility and Merits), Case 9903, Rafael Ferrer-Mazorra et al. (United States), April 4, 2001, paragraph 210, citing IACHR, Report on the Situation of Human Rights of Asylum Seekers within the Canadian Refugee Determination System, OEA/Ser.L/V/II.106, Doc. 40 rev., February 28,2000, paragraphs 134-142; ECHR, Case of Winterwerp, (1979) E.H.R.R. 387 and Case of Amuur v. France, (1996) 2 E.H.R.R. 553, paragraph 53. 157 IACHR, Report No. 51/01 (Admissibility and Merits), Case 9903, Rafael Ferrer-Mazorra et al. (United States), April 4, 2001, paragraph 212. See also, UN, Human Rights Committee A. v. Australia, Communication No. 560/1993, CCPR/C/59/D/560/1993, April 30, 1997, paragraph 9.4 158 IACHR, Admissibility and Merits Report No. 51/01, Case 9903, Rafael Ferrer-Mazorra et al. (The Mariel Cubans) (United States). April 4, 2001, paragraphs 216-219. 159 I/A Court H.R., Case of Vélez Loor v. Panama. Preliminary Objections, Merits, Reparations and Costs. Judgment of November 23, 2010. Series C No. 218, paragraph 170. There are citations. 160 I/A Court H.R., Case of Vélez Loor v. Panama. Preliminary Objections, Merits, Reparations and Costs. Judgment of November 23, 2010. Series C No. 218, paragraph 166.