A. AND OTHERS v. THE UNITED KINGDOM JUDGMENT 79 Norway, 29 August 1990, § 50, Series A no. 181-A). The reviewing “court” must not have merely advisory functions but must have the competence to “decide” the “lawfulness” of the detention and to order release if the detention is unlawful (see Ireland v. the United Kingdom, cited above, § 200; Weeks v. the United Kingdom, 2 March 1987, § 61, Series A no. 114; and Chahal, cited above, § 130). 203. The requirement of procedural fairness under Article 5 § 4 does not impose a uniform, unvarying standard to be applied irrespective of the context, facts and circumstances. Although it is not always necessary that an Article 5 § 4 procedure be attended by the same guarantees as those required under Article 6 for criminal or civil litigation, it must have a judicial character and provide guarantees appropriate to the type of deprivation of liberty in question (see, for example, Winterwerp v. the Netherlands, 24 October 1979, § 57, Series A no. 33; Bouamar v. Belgium, 29 February 1988, §§ 57 and 60, Series A no. 129; Włoch v. Poland, no. 27785/95, § 125, ECHR 2000-XI; and Reinprecht v. Austria, no. 67175/01, § 31, ECHR 2005-XII). 204. Thus, the proceedings must be adversarial and must always ensure “equality of arms” between the parties (see Reinprecht, cited above, § 31). An oral hearing may be necessary, for example in cases of detention on remand (see Nikolova v. Bulgaria [GC], no. 31195/96, § 58, ECHR 1999-II). Moreover, in remand cases, since the persistence of a reasonable suspicion that the accused person has committed an offence is a condition sine qua non for the lawfulness of the continued detention, the detainee must be given an opportunity effectively to challenge the basis of the allegations against him (see Becciev v. Moldova, no. 9190/03, §§ 68-72, 4 October 2005). This may require the court to hear witnesses whose testimony appears prima facie to have a material bearing on the continuing lawfulness of the detention (ibid., §§ 72-76, and Ţurcan v. Moldova, no. 39835/05, §§ 67-70, 23 October 2007). It may also require that the detainee or his representative be given access to documents in the case file which form the basis of the prosecution case against him (see Włoch, cited above, § 127; Nikolova, cited above, § 58; Lamy v. Belgium, 30 March 1989, § 29, Series A no. 151; and Fodale v. Italy, no. 70148/01, ECHR 2006-VII). 205. The Court has held nonetheless that, even in proceedings under Article 6 for the determination of guilt on criminal charges, there may be restrictions on the right to a fully adversarial procedure where strictly necessary in the light of a strong countervailing public interest, such as national security, the need to keep secret certain police methods of investigation or the protection of the fundamental rights of another person. There will not be a fair trial, however, unless any difficulties caused to the defendant by a limitation on his rights are sufficiently counterbalanced by the procedures followed by the judicial authorities (see, for example,