CDL-AD(2006)009 - 14 - 57. “Degrading treatment” is treatment which grossly humiliates or debases a person before others or drives him to act against his will or conscience. Although causing less suffering than torture or inhuman treatment, it must attain a minimum level27. It too does not need to be intended to cause suffering. 58. The prohibition of torture and inhuman or degrading treatment or punishment enshrines one of the most fundamental values of democratic societies. As the European Court of Human Rights has stated on many occasions, even in the most difficult circumstances, such as the fight against terrorism and organised crime, the ECHR prohibits in absolute terms torture and inhuman or degrading treatment or punishment. Unlike most of the substantive clauses of the ECHR and of Protocols Nos. 1 and 4, Article 3 makes no provision for limitations and no derogation from it is permissible under Article 15 § 2, not even in the event of a public emergency threatening the life of the nation. 59. Article 2, paragraph 2, of the UN Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (“the UN Convention against Torture”) expressly States that “No exceptional circumstances whatsoever, whether a State of war or a threat of war, internal political instability or any other public emergency, may be invoked as a justification of torture.” 60. The European Convention for the Prevention of Torture and Inhuman and Degrading Treatment (“ECPT”) establishes the European Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment (“CPT”) which, “by means of visits, examines the treatment of persons deprived of their liberty with a view to strengthening, if necessary, the protection of such persons from torture and from inhuman or degrading treatment or punishment.” Pursuant to Article 2 of this Convention, CPT can visit any place on the territory of member States where a person is deprived of their liberty (i.e. including military bases, nonofficial detention centres such as the offices of the intelligence service or a particular police department - drugs, anti-terrorism - if CPT believes that persons are being held/interviewed in these offices). 61. Member States of the ECHR not only have the obligation not to torture but also the duty to prevent torture.28 In addition they have an obligation of investigation. Under this obligation Member States must assure an efficient, effective and impartial investigation.29 As soon as the authorities receive substantiated information giving rise to the suspicion that torture or inhuman or degrading treatment has been committed, a duty to investigate arises whether and in which circumstances torture has been committed. 27 European Court of Human Rights, Tyrer v. United Kingdom judgment of 25 April 1978, § 29. 28 European Court of Human Rights, Z v. United Kingdom judgment of 10 May 2001; A. v. the United Kingdom judgment of 23 September 1998, § 22. 29 European Court of Human Rights, Caloc v. France judgment of 20 July 2000.