CCPR/C/GC/35 deprive them of review of the lawfulness of their detention. 182 The extraterritorial location of an arrest may be a circumstance relevant to an evaluation of promptness under paragraph 3. 64. With regard to article 4 of the Covenant, the Committee first observes that, like the rest of the Covenant, article 9 applies also in situations of armed conflict to which the rules of international humanitarian law are applicable.183 While rules of international humanitarian law may be relevant for the purposes of the interpretation of article 9, both spheres of law are complementary, not mutually exclusive.184 Security detention authorized and regulated by and complying with international humanitarian law in principle is not arbitrary. In conflict situations, access by the International Committee of the Red Cross to all places of detention becomes an essential additional safeguard for the rights to liberty and security of person. 65. Article 9 is not included in the list of non-derogable rights of article 4, paragraph 2, of the Covenant, but there are limits on States parties’ power to derogate. States parties derogating from normal procedures required under article 9 in circumstances of armed conflict or other public emergency must ensure that such derogations do not exceed those strictly required by the exigencies of the actual situation. 185 Derogating measures must also be consistent with a State party’s other obligations under international law, including provisions of international humanitarian law relating to deprivation of liberty, and nondiscriminatory.186 The prohibitions against taking of hostages, abductions or unacknowledged detention are therefore not subject to derogation. 187 66. There are other elements in article 9 that in the Committee’s opinion cannot be made subject to lawful derogation under article 4. The fundamental guarantee against arbitrary detention is non-derogable, insofar as even situations covered by article 4 cannot justify a deprivation of liberty that is unreasonable or unnecessary under the circumstances.188 The existence and nature of a public emergency which threatens the life of the nation may, however, be relevant to a determination of whether a particular arrest or detention is arbitrary. Valid derogations from other derogable rights may also be relevant when a deprivation of liberty is characterized as arbitrary because of its interference with another right protected by the Covenant. During international armed conflict, substantive and procedural rules of international humanitarian law remain applicable and limit the ability to derogate, thereby helping to mitigate the risk of arbitrary detention.189 Outside that context, the requirements of strict necessity and proportionality constrain any derogating measures involving security detention, which must be limited in duration and accompanied by procedures to prevent arbitrary application, as explained in paragraph 15 above,190 including review by a court within the meaning of paragraph 45 above.191 182 183 184 185 186 187 188 189 190 191 See concluding observations: United States of America (CCPR/C/USA/CO/3, 2006), paras. 12 and 18. General comments No. 31, para. 11, and No. 29, para. 3. General comments No. 31, para. 11, and No. 29, paras. 3, 12 and 16. General comment No. 29, paras. 4–5. When the emergency justifying measures of derogation arises from the participation of State party’s armed forces in a peacekeeping mission abroad, the geographic and material scope of the derogating measures must be limited to the exigencies of the peacekeeping mission. General comment No. 29, paras. 8–9. Ibid., para. 13 (b). Ibid., paras. 4 and 11. Ibid., para. 3. Ibid., paras. 4, 11 and 15. Ibid., para. 16; paragraph 67 below. 19