A/HRC/27/47 Working Group would like to acknowledge the very comprehensive contribution made by Oxford Pro Bono Publico at the University of Oxford, which submitted “Remedies and procedures on the right of anyone deprived of his or her liberty by arrest or detention to bring proceedings before a court: a comparative and analytical review of State practice” (April 2014). This has been of particular assistance to the Working Group in establishing State practice and the requisite opinio juris. 63. The Working Group recalls the statement by the International Court of Justice in Jurisdictional Immunities: “It is of course axiomatic that the material of customary international law is to be looked for primarily in the actual practice and opinio juris of States, even though multilateral conventions may have an important role to play in recording and defining rules deriving from custom, or indeed in developing them … In the present context, State practice of particular significance is to be found in the judgments of national courts”.21 In deliberation No. 9 (2012) concerning the definition and scope of arbitrary deprivation of liberty under customary international law,22 the Working Group adopted the approach to formation of customary international law currently restated in the work of the International Law Commission (A/CN.4/663) and reflected in the request by the Human Rights Council to produce the present report. When the Working Group applies the law, and when it finds violations of human rights obligations, it is bound by the general method of international law, in treaty interpretation and the application of customary international law. In addition to the materials presented in the present report to the Human Rights Council, important sources of international law can be found in the Council’s own procedures and their outcomes, with the additional reporting and peer-review procedures, including those of the universal periodic review. V. Conclusion 64. The present report demonstrates how the procedural guarantee has been developed in different international instruments, in regional legal frameworks, and in the domestic law of States from a diversity of legal traditions. The reaffirmation and clarification of the due process safeguard is a feature of international treaties and domestic legislation, the jurisprudence of international human rights mechanisms, including treaty bodies and special procedure mandate holders, regional human rights mechanisms and national courts. The procedural guarantee is viewed as an essential component of the due process rights that are necessary to protect the right to liberty and security of the person in all situations of deprivation of liberty and to prevent arbitrary arrest, detention or exile, enforced disappearance, or risk of torture and other cruel, inhuman or degrading treatment or punishment. The review of legal frameworks further confirms that, where it has been determined that the fundamental rights of the detainee have been violated, such wrongs demand a remedy. 65. The extensive survey undertaken of the relevant sources shows that the right to challenge the lawfulness of detention and the right to a remedy where there is a wrong is supported by uniform international practice, State practice and the opinio juris of States. It shows not only the existence of customary norms of international law that apply erga omnes, but also that these norms are peremptory rules, jus cogens, in 21 22 Jurisdictional Immunities of the State (Germany v. Italy: Greece intervening), Judgment, ICJ Reports 2012, p. 99, 122–23 [55]. Deliberation No. 9 has been cited as one source on the approach to identification of customary international law by Sir Michael Wood, First Report on formation and evidence of customary international law, International Law Commission, Sixty-fifth session, 17 May 2013, (A/CN.4/663, para. 53) and in Sir Michael’s Second Report (A/CN.4/672, paras 41.8 and 76.6). 19