Chapter 1 • International Human Rights Law and the Role of the Legal Professions: A General Introduction the degree of precision of the norms and undertakings defined therein, and the means foreseen for the control of their application; it will also depend on the number of countries having voted in favour thereof, and the circumstances of their adoption.28 A particularly relevant question in this respect would be whether the resolution concerned has been adopted in isolation or whether it forms part of a series of resolutions on the same subject with a consistent and universal content. v Peremptory norms (jus cogens): It should finally be noted that some legal norms, such as the prohibition of slavery, may be considered to be so fundamental that they are called peremptory norms of international law. According to article 53 of the Vienna Convention on the Law of Treaties, a treaty is simply “void if, at the time of its conclusion, it conflicts with a peremptory norm of international law”. According to the same article, such a norm is described as “a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character”. However, whenever the notion of peremptory norm is being discussed, disputes arise as to its exact contents, and consequently it will not be further dealt with in this Manual. 2.4.3 General principles of law recognized by the community of nations This third source of law cited by the Statute of the International Court of Justice helps ensure that, in cases where international treaties and customary law might provide an insufficient basis for the Court to take a decision, it will be able to draw on other resources. A general principle of law, as a source of international human rights law, is a legal proposition so fundamental that it can be found in all major legal systems throughout the world. If there is evidence that, in their domestic law, States adhere to a particular legal principle which provides for a human right or which is essential to the protection thereof, then this illustrates the existence of a legally binding principle under international human rights law. Judges and lawyers can thus look to other legal systems to determine whether a particular human rights principle is so often accepted that it can be considered to have become a general principle of international law. Domestic law analogies have thus, for instance, been used in the field of principles governing the judicial process, such as the question of evidence.29 2.4.4 Subsidiary means for the determination of rules of law As subsidiary means for the determination of rules of law, article 38 of the Statute mentions “judicial decisions and the teachings of the most highly qualified publicists”. As previously mentioned, in the human rights field, judicial decisions are particularly important for a full understanding of the law, and the wealth of international case-law that now exists in this field must be regarded as authoritative evidence of the state of the law. However, neither the International Court of Justice nor 28 For some of these elements, see e.g. Les résolutions dans la formation du droit international du développement, Colloque des 20 et 21 novembre 1970, L’Institut universitaire de hautes études internationales, Genève, 1971 (Études et travaux, No. 13), pp. 9, 30-31 (intervention by Professor Virally). 29 Ian Brownlie, Principles of Public International Law (Oxford, Clarendon Press, 1979), 3rd edn., 1979, p. 18. Human Rights in the Administration of Justice: A Manual on Human Rights for Judges, Prosecutors and Lawyers 11