for the relevant offence, having regard to the state’s involvement in the circumstances in which it was committed. To prosecute in a case where the state has procured the commission of the crime is (para 19) “unacceptable and improper” and “an affront to the public conscience.” Such a prosecution would not be fair in the broad sense of the word. My noble and learned friend Lord Hoffmann, having referred to Canadian authority and to Bennett, accepted Lord Griffiths’ description of the power to stay in the case of behaviour which threatened basic human rights or the rule of law as (para 40) “a jurisdiction to prevent abuse of executive power”. THE EUROPEAN CONVENTION ON HUMAN RIGHTS 23. If, contrary to their submission (and to the opinion of the Divisional Court in R (Saifi) v Governor of Brixton Prison: see para 13 above) the common law and section 78 of the 1984 Act are not, without more, enough to require rejection of evidence which has or may have been procured by torture, whether or not with the complicity of the British authorities, the appellants submit that the European Convention compels that conclusion. 24. It is plain that SIAC (and, for that matter, the Secretary of State) is a public authority within the meaning of section 6 of the Human Rights Act 1998 and so forbidden to act incompatibly with a Convention right. One such right, guaranteed by article 3, is not to be subjected to torture or to inhuman or degrading treatment. This absolute, nonderogable prohibition has been said (Soering v United Kingdom (1989) 11 EHRR 439, para 88) to enshrine “one of the fundamental values of the democratic societies making up the Council of Europe”. The European Court has used such language on many occasions (Aydin v Turkey (1997) 25 EHRR 251, para 81). 25. Article 6 of the Convention guarantees the right to a fair trial. Different views have in the past been expressed on whether, for purposes of article 6, the proceedings before SIAC are to be regarded as civil or criminal. Rather than pursue this debate the parties are agreed that the appellants’ challenge to their detention pursuant to the Secretary of State’s certification in any event falls within article 5(4). That provision entitles anyone deprived of his liberty by arrest or detention to take proceedings by which the lawfulness of his detention shall be decided speedily by a court and his release ordered if the detention is not lawful. It is well-established that such proceedings must satisfy the -14-