46 GÄFGEN v. GERMANY JUDGMENT Convention against Torture (see paragraph 64 above), in particular, was cast in narrower terms. The United Nations Human Rights Committee, for instance, in its General Comment No. 7 of 30 May 1982 (see paragraph 70 above) had found that, in order to secure effective control of the prohibition of torture, it was essential to make both confessions and other evidence obtained through torture or inhuman or degrading treatment inadmissible in court. Likewise, the Supreme Court of Appeal of South Africa, in its judgment of 10 April 2008 in the case of Mthembu v. The State (see paragraph 74 above), had held that any use of evidence obtained by torture, including real evidence derived from it, rendered proceedings unfair. This had to apply in equal measure to other forms of ill-treatment. The findings of the Court in its judgments in Jalloh (cited above, §§ 99 and 104-07) and Harutyunyan v. Armenia (no. 36549/03, § 63, ECHR 2007-III) pointed in the same direction. 3. The Court’s assessment (a) Recapitulation of the relevant principles 162. The Court reiterates that its duty, pursuant to Article 19 of the Convention, is to ensure the observance of the engagements undertaken by the Contracting States to the Convention. In particular, it is not its function to deal with errors of fact or of law allegedly committed by a national court unless and in so far as they may have infringed rights and freedoms protected by the Convention. While Article 6 guarantees the right to a fair hearing, it does not lay down any rules on the admissibility of evidence as such, which is primarily a matter for regulation under national law (see Schenk v. Switzerland, 12 July 1988, §§ 45-46, Series A no. 140; Teixeira de Castro v. Portugal, 9 June 1998, § 34, Reports 1998-IV; and Heglas v. the Czech Republic, no. 5935/02, § 84, 1 March 2007). 163. It is not, therefore, the role of the Court to determine, as a matter of principle, whether particular types of evidence – for example, evidence obtained unlawfully in terms of domestic law – may be admissible. The question which must be answered is whether the proceedings as a whole, including the way in which the evidence was obtained, were fair. This involves an examination of the unlawfulness in question and, where the violation of another Convention right is concerned, the nature of the violation found (see, inter alia, Khan v. the United Kingdom, no. 35394/97, § 34, ECHR 2000-V; P.G. and J.H. v. the United Kingdom, no. 44787/98, § 76, ECHR 2001-IX; and Allan v. the United Kingdom, no. 48539/99, § 42, ECHR 2002-IX). 164. In determining whether the proceedings as a whole were fair, regard must also be had as to whether the rights of the defence have been respected. In particular, it must be examined whether the applicant was given an opportunity to challenge the authenticity of the evidence and to