United States was in violation of international standards from 2002 to 2008 by not allowing detainees to challenge the lawfulness of their detention in accordance with international humanitarian law or international human rights law. 173. The PRB also assesses the possibility for a detainee’s release. Similar to CSRTs and the ARB, the PRB is an administrative mechanism. It does not assess the lawfulness of detention, but instead analyses the detainee’s threat to the United States if released.244 The IACHR has concluded that the PRB falls short of the standards required by the ICRC regarding the independence and impartiality of any review body in the context of armed conflicts.245 The PRB only held its first hearing in 2013 by which time detainees were already able to challenge their detention in court. Since detainees already had an avenue to challenge their detention in court, the existence of the PRB is not relevant to assessing whether the United States complied with international standards in relation to the obligation to ensure that detainees have access to a court to challenge the lawfulness of their detention. This mechanism, however, will be discussed in Part 3 of this report in relation to the closure of Guantánamo. 174. Even though the United States Supreme Court determined that Guantánamo detainees have the right to habeas corpus hearings in 2008, some detainees have waited years for US courts to rule on their petitions.246 For instance, Obaidullah filed his habeas corpus petition in July 2008. The Bush administration subsequently filed charges against him, which were later withdrawn. Before the charges were withdrawn, his habeas corpus petition was held in abeyance from 2008 to June 2010.247 International law stipulates that challenges to the lawfulness of detention must be determined without delay, usually within several weeks.248 While the particular circumstances of a case may justify some delay, ODIHR considers that a delay of over two years is a substantial delay in violation of the prohibition of arbitrary detention.249 175. Contrary to international standards, US courts have not ordered the immediate release of detainees following successful habeas corpus petitions. This has allowed the US government to continue to unlawfully hold detainees at Guantánamo for extended periods were not held before an independent and impartial tribunal”, “CSRT is not an adequate and effective substitution to habeas corpus proceedings, and the Working Group has itself previously stated that ‘the procedures of the CSRT and the ARB are not adequate ... to satisfy the right to a fair and independent trial as these are military tribunals of a summary nature.’”; UN Special Rapporteur on human rights and counter-terrorism, Report to the General Assembly, A/63/223, op. cit., note 55, para. 22. 244 ODIHR meeting with the Special Envoys for Guantánamo Closure and the National Security Council, 4 September 2014. 245 IACHR, “Towards the Closure of Guantanamo”, 3 June 2015, paras. 262-265, <http://www.oas.org/en/iachr/reports/pdfs/Towards-Closure-Guantanamo.pdf>. 246 Article 9(4) of the ICCPR requires the court be able to “decide without delay on the lawfulness of his detention and order his release if the detention is not lawful”. 247 UN Working Group on arbitrary detention, Obaidullah v. United States of America, op. cit., note 197, paras. 8, 17; “I Am Fallen into Darkness: The Case of Obaidullah, Guantánamo Detainee Now in His 12th Year without Trial", Amnesty International, July 2013, p. 14, <http://www.amnestyusa.org/sites/default/files/amr510512013en.pdf>. His habeas corpus petition was subsequently denied in October 2010. United States District Court for the District of Columbia, Obaydullah v. Barack H. Obama, No. 08-1173, 19 October 2010, <https://casetext.com/case/obaydullah-v-obama-6?page=349>. 248 UN HRC, General Comment No. 35, op. cit., note 92, para. 47; Nowak, CCPR Commentary, op. cit., note 93, p. 236. 249 See, also, UN Working Group on arbitrary detention, Obaidullah v. United States of America, op. cit., note 197, paras. 35, 44: “The two-year delay in allowing Mr. Obaidullah to challenge his detention is a grave and clear violation, further aggravated by his continued detention [of Article 9(4) of the ICCPR].” The Working Group on arbitrary detention also determined that Obaidullah’s detention in general was arbitrary. 71