141. Customary international humanitarian law also prohibits arbitrary detention in international and non-international armed conflicts.134 The Third and Fourth Geneva Conventions, as well as Article 75 of API, govern the detainment of combatants and civilians during international armed conflicts. The Third Geneva Convention allows for the detention of combatants as prisoners of war until the end of active hostilities.135 While an administrative or judicial review of the lawfulness of detention is not generally required for prisoners of war, as the lawfulness of such detention is presumed, a competent tribunal must determine the individual’s status if there are doubts as to whether the person falls within the category of a prisoner of war under Article 4 of the Third Geneva Convention.136 The Fourth Geneva Convention allows for civilians to be interned or placed in assigned residence in exceptional circumstances, when they are either an alien civilian within the territory of a party to the international conflict (Article 42) or a civilian within an occupied territory (Article 78). Civilians are only to be detained in exceptional cases. Detention under Article 42 of the Fourth Geneva Convention is permissible only when it is “absolutely necessary” for the detaining country’s security. The detention of civilians in occupied territory is permissible only if it is “necessary, for imperative reasons of security”.137 Civilians detained during international armed conflicts are to have their detention “reconsidered as soon as possible by an appropriate court or administrative board” (in the case of detention under Article 42) or “subject to periodical review, if possible every six months, by a competent body” (in the case of detention under Article 78).138 Such review must be undertaken by a body that offers the necessary guarantees of independence and impartiality.139 Article 75 of API provides that detained persons maintain the right to be promptly informed of the reasons for detention in a language they understand.140 134 “Customary International Humanitarian Law, Rule 99: Deprivation of Liberty”, ICRC website, <https://www.icrc.org/customary-ihl/eng/docs/v1_rul_rule99>. 135 Third Geneva Convention, Art. 21: “The Detaining Power may subject prisoners of war to internment. It may impose on them the obligation of not leaving, beyond certain limits, the camp where they are interned, or if the said camp is fenced in, of not going outside its perimeter. Subject to the provisions of the present Convention relative to penal and disciplinary sanctions, prisoners of war may not be held in close confinement except where necessary to safeguard their health and then only during the continuation of the circumstances which make such confinement necessary.” See, also, Third Geneva Convention, Art. 118: “Prisoners of war shall be released and repatriated without delay after the cessation of active hostilities.” 136 Third Geneva Convention, Art. 5. See, also, “International Humanitarian Law and the Challenges of Contemporary Armed Conflicts”, ICRC, September 2007, op. cit., note 18, pp. 726-727. 137 Fourth Geneva Convention, Art. 42: “The internment or placing in assigned residence of protected persons may be ordered only if the security of the Detaining Power makes it absolutely necessary”; Art. 78: “If the Occupying Power considers it necessary, for imperative reasons of security, to take safety measures concerning protected persons, it may, at the most, subject them to assigned residence or to internment.” See, also, Art. 68: “Protected persons who commit an offence which is solely intended to harm the Occupying Power, (…) shall be liable to internment or simple imprisonment, provided the duration of such internment or imprisonment is proportionate to the offence committed”; Art. 41 on non-repatriated persons assigned to residence or internment and Art. 79 on cases of internment and applicable provisions. See, also, “Customary International Humanitarian Law, Rule 99”, ICRC website, op. cit., note 134. 138 Fourth Geneva Convention, Art. 43: “Any protected person who has been interned (…) shall be entitled to have action reconsidered as soon as possible by an appropriate court or administrative board designated by the Detaining Power for that purpose.”; Art. 78: “Decisions regarding such assigned residence or internment shall be made according to a regular procedure to be prescribed by the Occupying Power in accordance with the provisions of the present Convention. This procedure shall include the right of appeal for the parties concerned. Appeals shall be decided with the least possible delay. In the event of the decision being upheld, it shall be subject to periodical review, if possible every six months, by a competent body set up by the said Power”; “International Humanitarian Law and the Challenges of Contemporary Armed Conflicts”, ICRC, September 2007, op. cit., note 18, p. 728: “ after the end of an international armed conflict, the Fourth Geneva Convention can no longer be considered a valid legal framework for the detention of persons who are not subject to criminal proceedings”. See, also, Pejic, “Procedural Principles and Safeguards”, op. cit., note 16, pp. 386-387; Milanović, op. cit., note 10, p. 249. 139 Commentary on Art. 43, Fourth Geneva Convention, ICRC website, <https://www.icrc.org/applic/ihl/ihl.nsf/1a13044f3bbb5b8ec12563fb0066f226/b76d6efa7c1a4956c12563cd0042c193>; 56