- 29 - CDL-AD(2006)009 secrecy has on the prisoner’s defence rights under Articles 579 and 6 ECHR. In addition, prolonged secret detention may impinge on Article 380 and on other aspects of Article 6 ECHR. 122. For a State to provide facilities to another State to conduct voluntary interviews with suspects on its territory is, in principle, not in violation of international law. On the contrary, it is a feature of most modern Mutual Assistance Treaties. It depends upon the territorial States’ constitutional and administrative rules on the exercise of public power whether this can go so far as involuntary interrogation. Some States will not allow any but their own officials to exercise public power on their territory. Others make exceptions by treaty rules81. 123. The territorial State retains its full jurisdiction within the meaning of Article 1 ECHR over any place on its territory where such interviews take place, including any ad hoc detention facilities: : that State is therefore responsible for any infringement of the ECHR in relation to any suspect treated in violation of Articles 3 and 5, e.g. any prisoners who may be held incomunicado there. The modalities of the interrogation and detention, and of treatment given, need to comply with the standards of the European Convention on Human Rights. 124. Incomunicado detention, that is detention without the possibility of contacting one’s lawyer and of applying to a court, is clearly not “in accordance with a procedure prescribed by law” of any of the member States of the Council of Europe, if alone because the detention is not subject to judicial review. For the detainee, it is not possible to exercise his entitlement to habeas corpus guaranteed by Article 5, paragraph 4. The unlike possibility that such a detention is “in accordance with a procedure prescribed by law” under the law of the foreign State by whose authorities the detention was ordered and executed, is irrelevant for the issue of the responsibility under the European Convention on Human Rights of the State on whose territory it takes place. 125. If and in so far as incomunicado detention takes place, is made possible or is continued on the territory of a member State of the Council of Europe, in view of its secret character that detention is by definition in violation of the European Convention on Human Rights and the applicable domestic law of that State. 126. Active and passive co-operation by a Council of Europe member State in imposing and executing secret detentions engages its responsibility under the European Convention on Human Rights. The European Court of Human Rights has ruled that “the acquiescence or connivance of the authorities of a Contracting State in the acts of private individuals which violate the Convention rights of other individuals within its jurisdiction may engage the State’s responsibility under the Convention”82. This is even more true in respect of acts of agents of foreign States. 79 European Court of Human Rights, Kurt v. Turkey judgment of 25 May 1998, § 124. 80 Inter-American Court of Human Rights, Velasquez Rodrigues case, 29 July 1988, § 187 and Suarez Rosero case, 12 November 1997, §§ 90-91. UN Human Rights Committee, Polay Campos v. Peru, Communication 577/1994, 6 November 1997, §§ 8.4, 8.6 and 8.7. See also European Court of Human Rights, Ocalan v. Turkey judgment of 12 March 1993, §§ 31-232. 81 The Schengen Treaty, for example. 82 European Court of Human Rights, Ilascu and others v. Moldova and Russia judgment of 8 July 2004, § 318.