(6) The rationale of the exclusionary rule in article 15 is found not only in the general unreliability of evidence procured by torture but also in its offensiveness to civilised values and its degrading effect on the administration of justice. (7) Measures directed to counter the grave dangers of international terrorism may not be permitted to undermine the international prohibition of torture. It is necessary to examine these propositions in a little detail. (1) Interpretation of the Convention in a wider international context. 29. Article 31 of the Vienna Convention on the Law of Treaties, reflecting principles of customary international law, provides in article 31(3)(c) that in interpreting a treaty there shall be taken into account, together with the context, any relevant rules of international law applicable in the relations between the parties. The European Court has recognised this principle (Golder v United Kingdom (1975) 1 EHRR 524, para 29, HN v Poland (Application No 77710/01, 13 September 2005, unreported, para 75)), and in Al-Adsani v United Kingdom (2001) 34 EHRR 273, para 55, it said (footnotes omitted): “55. The Court must next assess whether the restriction was proportionate to the aim pursued. It recalls that the Convention has to be interpreted in the light of the rules set out in the Vienna Convention of 23 May 1969 on the Law of Treaties, and that Article 31(3)(c) of that treaty indicates that account is to be taken of ‘any relevant rules of international law applicable in the relations between the parties’. The Convention, in including Article 6, cannot be interpreted in a vacuum. The Court must be mindful of the Convention’s special character as a human rights treaty, and it must also take the relevant rules of international law into account. The Convention should so far as possible be interpreted in harmony with other rules of international law of which it forms part, including those relating to the grant of State immunity.” The Court has in its decisions invoked a wide range of international instruments, including the United Nations Convention on the Rights of the Child 1989 and the Beijing Rules (V v United Kingdom (1999) 30 -19-