A/HRC/13/42* page 28 prohibition of enforced disappearance is a rule of customary international humanitarian law applicable in all situations of armed conflict.64 56. As incommunicado detention is also prohibited under international humanitarian law applicable to all armed conflicts65 and to all persons who no longer take direct part in hostilities,66 detainees must be registered, provided an effective opportunity to immediately inform their family and a centralized information bureau of their detention and any subsequent transfer, and must be permitted ongoing contact with family members and others outside the place of detention.67 Article 5 of the Fourth Geneva Convention permits the detaining power to deny to persons these rights and privileges “where absolute military security so requires” when an individual found physically in the State’s own territory is “definitely suspected of or engaged in activities hostile to the security of the State”, or when an individual in occupied territory is “detained as a spy or saboteur, or as a person under definite suspicion of activity hostile to the security of the Occupying Power”. While the article states that these persons “shall also be granted the full rights and privileges of a protected person under the present Convention at the earliest date consistent with the security of the State or Occupying Power”, ICRC stresses that article 5 may only be applied in individual cases of an exceptional nature, when the existence of specific charges makes it almost certain that penal proceedings will follow. Bare suspicion of hostile activities would not suffice; it would have to be a definite suspicion of such activities. The burden of definite suspicion is a high burden that must be individualized and must not be of a general nature.68 III. SECRET DETENTION PRACTICES IN PAST CONTEXTS A. The emergence of the recent practice of secret detention 57. The phenomenon of secret detention, closely intertwined with enforced disappearances, can be traced at least to the Nacht und Nebel Erlaß of the Nazi Germany, the “night and fog decree”, according to which suspected resistance movement members could be arrested in occupied Europe and secretly transferred to Germany “under cover of night”.69 These measures 64 Henckaerts and Doswald-Beck, op.cit., pp. 340-343. 65 Ibid., pp. 344-352. 66 Ibid., p. 299. 67 Third Geneva Convention, art. 48, 70 and 122; and Fourth Geneva Convention, art. 25, 26, 41, 78, 79, 106, 107, 116, 128 and 136. 68 Commentary to Convention (IV) Relative to the Protection of Civilian Persons in Time of War, Geneva, 12 August 1949, art. 5, available at www.icrc.org. 69 Christopher K. Hall, “Enforced disappearance of persons”, in Otto Triffterer (ed.), Commentary on the Rome Statute of the International Criminal Court, Baden-Baden 1999, p. 151, with further related references.