ÇAKICI v. TURKEY JUDGMENT 27 was also no prompt and effective investigation by the authorities into the family’s claim that Ahmet Çakıcı had been taken into custody, which, in the applicant’s view, constituted a separate violation of Article 5. 102. The Government, denying that Ahmet Çakıcı was taken into custody, maintained that the authorities furnished to the applicant all available information concerning his brother, in particular as regards the fact that his name did not appear in any custody record. They submitted that the Commission’s criticism of the custody registers was irrelevant to the facts of this case and, in any event, disproportionate. They took the view that it would not be possible to hold persons in detention for the period alleged without properly recording them in the relevant registers or instituting the appropriate judicial procedures. They also referred to their derogation under Article 15, citing the Aksoy case (Aksoy v. Turkey judgment of 18 December 1996, Reports 1996-VI) in which the Court acknowledged the existence of a public emergency threatening the life of the nation as a result of the terrorist threat in south-east Turkey. 103. The Commission, finding that Ahmet Çakıcı had been arbitrarily deprived of his liberty by the security forces, held that the Government had not provided a credible or substantiated explanation of what had happened to him. When examining the safeguards in place to protect a detained person from involuntary disappearance, it observed that the custody registers for Lice, Hazro and Diyarbakır provincial gendarmerie headquarters disclosed omissions, irregularities and inconsistencies such that they could no longer be regarded as reliable or accurate. It was also not satisfied that the gendarmes were properly aware of, or put into practice, correct and effective registration procedures. 104. The Court has frequently emphasised the fundamental importance of the guarantees contained in Article 5 for securing the rights of individuals in a democracy to be free from arbitrary detention at the hands of the authorities (see, amongst others, the Kurt judgment cited above, pp. 118485, § 122). In that context, it has repeatedly stressed that any deprivation of liberty must not only have been effected in conformity with the substantive and procedural rules of national law but must equally be in keeping with the very purpose of Article 5, namely to protect the individual from arbitrary detention (see, amongst other authorities, the Chahal v. the United Kingdom judgment of 15 November 1996, Reports 1996-V, p. 1864, § 118). To minimise the risks of arbitrary detention, Article 5 provides a corpus of substantive rights intended to ensure that the act of deprivation of liberty is amenable to independent judicial scrutiny and secures the accountability of the authorities for that measure. As the Court previously held in the Kurt case (Kurt judgment cited above, p. 1185, § 124), the unacknowledged detention of an individual is a complete negation of these guarantees and discloses a most grave violation of Article 5. Given the responsibility of the authorities to account for individuals under their control, Article 5 requires