10 United Nations Convention Against Torture and its Optional Protocol 4.  Rules of Interpretation According to Article 31 VCLT, an international treaty ‘shall be interpreted . . . in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in light of its object and purpose’. Thus, of primary significance is the textual, contextual, systematic and teleological interpretation, whereby, in addition to the treaty wording, consideration is also given to the Preamble.48 The object and purpose of the Convention and Protocol can be derived from the desire of the drafters, as laid down in the respective Preambles: on the one side to make the struggle against torture and cruel, inhuman or degrading treatment or punishment ‘more effective’ and, on the other side, to strengthen the protection of persons deprived of their liberty against torture and other forms of ill-​treatment by establishing a system of preventive visits to all places of detention. Any interpretation which would lead to the weakening of already existing norms for the prohibition and prevention of torture and cruel, inhuman or degrading treatment or punishment has thus been avoided. Systematic interpretation may be facilitated by a comparative analysis of similar international or regional human rights treaties, such as the CCPR, the Inter-​American Convention to Prevent and Punish Torture 1985, or the ECPT. The subsequent practice of States parties, to be considered pursuant to Article 31(3) VCLT, can in part be derived from relevant reservations and declarations of interpretation, as well as from State reports and observations submitted by States parties. Human rights texts are often characterized by a high degree of abstraction and vagueness. If the textual, contextual, systematic, and teleological interpretation ‘leaves the meaning ambiguous or obscure, or leads to a result which is manifestly absurd or unreasonable’, Article 32 VCLT permits additional tools to be drawn upon, in particular, the preparatory work of the treaty (‘travaux préparatoires’). The historical background of the CAT and the OP, above all the detailed discussions in the respective inter-​sessional Working Groups of the UN Commission on Human Rights, has been outlined in relation to every Article and was used in the present Commentary as a source of interpretation whenever the meaning of a certain provision remained ambiguous. The most important sources of information used in this Commentary as a tool for interpreting the provisions of the Convention is the practice of the Committee against Torture, be it in the State reporting, individual complaints and inquiry procedures. The same is valid for the practice of the SPT with regard to the Optional Protocol. In particular, decisions and statements of the Committee based on consensus rank highly in the interpretation of the Convention, even though these are not internationally binding. For the purpose of the present Commentary, the entire case law on individual complaints, the ‘General Comments’, country-​specific comments, and observations in the State reporting procedure, as well as the reports in the inquiry procedure have been treated as an ‘authoritative interpretation’ of the relevant provisions of the Convention. The case law and practice of other treaty monitoring bodies, such as the UN Human Rights Committee, Special Procedures of the Human Rights Council, above the Special Rapporteur on Torture, as well as regional bodies, such as the European, African, and Inter-​American 48   See eg Ian Brownlie, Principles of Public International Law (5th edn, Clarendon Press 1998) 605; Manfred Nowak, UN Covenant on Civil and Political Rights: CCPR Commentary (2nd rev edn, NP Engel 2005) (CCPR Commentary) XXVI.