A/66/268 Political Rights, torture as defined in article 1 of the Convention against Torture or cruel, inhuman or degrading punishment as defined in article 16 of the Convention. 71. The assessment of whether solitary confinement amounts to torture and other cruel, inhuman or degrading treatment or punishment should take into consideration all relevant circumstances on a case-by-case basis. These circumstances include the purpose of the application of solitary confinement, the conditions, length and effects of the treatment and, of course, the subjective conditions of each victim that make him or her more or less vulnerable to those effects. In this section, the report discusses a few circumstances where the use of solitary confinement constitutes torture and other cruel, inhuman or degrading treatment or punishment. 72. Solitary confinement, when used for the purpose of punishment, cannot be justified for any reason, precisely because it imposes severe mental pain and suffering beyond any reasonable retribution for criminal behaviour and thus constitutes an act defined in article 1 or article 16 of the Convention against Torture, and a breach of article 7 of the International Covenant on Civil and Political Rights. This applies as well to situations in which solitary confinement is imposed as a result of a breach of prison discipline, as long as the pain and suffering experienced by the victim reaches the necessary severity. 73. While physical and social segregation may be necessary in some circumstances during criminal investigations, the practice of solitary confinement during pretrial detention creates a de facto situation of psychological pressure which can influence detainees to make confessions or statements against others and undermines the integrity of the investigation. When solitary confinement is used intentionally during pretrial detention as a technique for the purpose of obtaining information or a confession, it amounts to torture as defined in article 1 or to cruel, inhuman or degrading treatment or punishment under article 16 of the Convention against Torture, and to a breach of article 7 of the International Covenant on Civil and Political Rights. 74. Where the physical conditions of solitary confinement are so poor and the regime so strict that they lead to severe mental and physical pain or suffering of individuals who are subjected to the confinement, the conditions of solitary confinement amount to torture or to cruel and inhuman treatment as defined in articles 1 and 16 of the Convention, and constitute a breach of article 7 of the Covenant. 75. The use of solitary confinement can be accepted only in exceptional circumstances where its duration must be as short as possible and for a definite term that is properly announced and communicated. Given the harmful effects of indefinite solitary confinement, its potential use to extract information or confession during pretrial detention, and the fact that uncertainty prevents the use of remedies to challenge it, the Special Rapporteur finds that indefinite imposition of solitary confinement violates the right to due process of the concerned individual (article 9 of the Covenant, articles 1 or 16 of the Convention, and article 7 of the Covenant). 76. The Special Rapporteur asserts that social isolation is contrary to article 10, paragraph 3, of the International Covenant on Civil and Political Rights, which states that “The penitentiary system shall comprise treatment of prisoners the essential aim of which shall be their reformation and social rehabilitation” (General Assembly resolution 2200 (XXI), annex). Long periods of isolation do not aid the 20 11-44570