CYIL vol. 14 (2023)

PETRA RUFFER LUSTIGOVÁ CYIL 14 (2023) though individual states may find short-term advantages in violating the law in particular situations, their long-term interests are likely to be served best by the system. 26 The origins of international law stem from the needs of sovereign states to ensure stability and predictability of their mutual expectations based on reciprocal norms of behaviour 27 generally recognised as rational, convenient, and commonly regarded as worth of following. To this end “ [b]e that as it may, the system of international law serves the principal interests of states ”. 28 3.2 The origins and sources of international law Contemporary international law consists primarily of treaties (which create rules binding upon the signatories) and customary rules (state practices recognised by the community at large as laying down patterns of conduct that have to be complied with). 29 Other sources of international law, complementary to the treaties, and to the international custom, are (as further enumerated in Article 38 of the Statute of the International Court of Justice) the general principles of law recognized by civilized nations; and as subsidiary means for determination of rules of law also judicial decisions and the teachings of the most highly qualified publicists. Article 38 of the ICJ Statute does not mention resolutions or decisions of international organs as either a principal source or subsidiary means of determining applicable international law. 30 In the context of the United Nations, it is the Security Council that has certain compulsory powers when acting under Chapter VII of the Charter. Except for certain resolutions of the General Assembly that are binding upon the organs and Member States of the UN, 31 resolutions of the General Assembly are “ merely recommendatory, putting forward opinions on various issues with varying degrees of majority support ”, 32 nevertheless they “ may sometime have normative value. They can, in certain circumstances, provide evidence important for establishing the existence of a rule or the emergence of an opinio juris ”. 33 Article 38 of the ICJ Statute does not enumerate unilateral acts of states that are by some authors considered to be sources of international law as well, despite their unclear stance. 34 Given its historical origin and gradual development, international law originates in “ a system of customary law, upon which has been erected, almost entirely within the last two generations, a superstructure of ‘conventional’ or treaty-made law ”. 35 A norm of customary law is established if there is evidence of sufficient practice in conformity with the rule, and general acceptation 26 See further , Charney, supra note 20 , p. 531. 27 See further, Henkin et al., supra note 12 , p. 20 (reference to Hans Kelsen, Pure Theory of Law (1967), pp. 215–217). 28 Charney, supra note 20 , p. 532. 29 Shaw, supra note 22 , p. 6. 30 HENKIN, L. et al., International Law: Cases and Materials (West Publishing Co., 5 th ed., 1993), p. 265. 31 According to Article 17 of the UN Charter. 32 Shaw, supra note 22 , p. 90. 33 Nuclear Weapons Case (Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion of 8 July 1996), ICJ Reports (1996), para 70. Resolutions illustrating some of those issues are, for example, the Universal Declaration on Human Rights (1948), the Declaration on Principles of International Law Concerning Friendly Relations Between States (1970) or the Definition of Aggression Resolution (1974). See further, Henkin, supra note 30, p. 266.. 34 ČEPELKA, Č., ŠTURMA, P. Mezinárodní právo veřejné , [Public International Law], (C. H. Beck, 2 nd ed., 2018), p. 114. 35 Harris, supra note 6 , p. 3 (reference to Brierly, The Law of Nations, 6 th ed., 1963, pp. 41–42, 68–76).

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