principles include, for example, the principle of good faith,31 and the principle of non bis in idem (no one shall be tried twice for the same offence).32 11. In addition there are a range of ‘soft law’ documents and principles including declarations adopted by the UN General Assembly, such as the Universal Declaration on Human Rights, guidelines, rules and regulations. Whilst these may be adopted under the auspices of an international organisation, such as the UN or the Arab League, they may not be intended to create legal obligations on the State parties. They are however authoritative sources of rights and how they should be applied. 12. Further sources of soft law include statements from those responsible for implementing human rights treaties, such as the General Comments and the decisions on communications of the UN treaty bodies such as the Human Rights Committee under the ICCPR. Although these are highly respected, there is some debate over whether they are binding. This is to be contrasted with decisions of international courts such as the Inter-American Court of Human Rights, the African Court of Human and Peoples’ Rights and the European Court of Human Rights whose judgments are binding on the State party to the litigation. In this manual all sources of human rights are relied upon. B. The position of international human rights law in domestic law 13. The Vienna Convention provides that a treaty obligation is binding upon the States parties, that it must be performed in good faith and that the parties cannot invoke domestic legislation as a justification for their failure to perform their obligation.33 Beyond this, States generally have significant discretion in how they choose to incorporate international law into domestic law or in implementing their international legal obligations. State practice, however, reveals two major approaches which are based on two different theories regarding the relationship between international law and domestic law and the mechanisms used to ensure compliance with international obligations. The two major approaches are known as the monist and dualist theories. 14. For the strictly monist theory, international law and domestic law are not separate but belong to the same legal order. Accordingly, a treaty becomes part of domestic law upon ratification or accession by a State, without the need to take further measures for its incorporation into domestic law. For the dualist doctrine, however, international and national laws belong to two separate legal systems. As such, it is necessary that the State authorities enact an implementing legislation for an international treaty to be applicable at the domestic level. The introduction of the treaty into domestic law may take the form of a domestic legislation adopting the text of the treaty or a piece of 31 ICJ, Nuclear Tests Cases (Australia v France; New Zealand v France), [1974] ICJ Reports p.253. See Chorzow´ Factory Case (Interpretation) (1927) PCIJ Ser. A 9, at p. 27. 33 Articles 26 and 27 of the Vienna Convention on the Law of Treaties. 32 24