현대 국제관습법의 형성에 관한 연구

초록

Customary law is, as the oldest source of law in general and of international law, one of the primary sources of international law. Paragraph 1 (b), article 38 of the I.C.J. Statute on "international custom, as evidence of a general practice accepted as law," despite the problem in the wording, has been considered as an authoritative statement of customary international law(hereinafter, "CIL"). According to this provision, the constitutive elements of CIL are twofold: objective element of general practice and subjective element of opinio juris. It has been accepted that CIL is traditionally established through the inter state interaction and acquiescence of States with long-term and consistent repetition of state practice and opinio juris, especially based on not word but act. This view has been assessed as a traditional understanding on the formation of CIL since the 19th century. However, due to changes in the international society in the late 20th century, new understanding on the formation of CIL has been proposed. According to the new formation theory, the essence of CIL is opinio juris as the normative will of States, so CIL can be created only with opinio juris even without state practice because state practice just supplies the evidence for opinio juris. Compared with the traditional understanding, this new one has different theoretical basis. Thus, today, there exist two different understandings on the formation of CIL. Especially, concerning the legal evaluation on resolutions and declarations of international organizations or conventions, there are some conflicting issues. In other words, there are confrontations between new and traditional understandings - respectively, positive and negative to the formation - over the contribution of resolutions of international organizations or conventions, especially of the UN General Assembly, on the formation of CIL and, if any, through what kind of method. This confrontation was accelerated by the Nicaragua case of the I.C.J., but on the other side, the case was a starting point to integrate these different formation theories of CIL. There could be a clue for the solution of the extreme theoretical differences surrounding the current formation theories of CIL. In the rulings concerned, the I.C.J. has continuously maintained that CIL is established by state practice and opinio juris and has shown the tendency to consider resolutions and declarations as international custom-creating practice. Therefore, it is alleged that the CIL is established by various kinds of state practice. I can be cautiously said that the formation of current CIL starts with various kinds of state practice, based on expanding scope of state practice as the basis for the formation of CIL, from actual state activities to declarations or statements of States which show stance and attitude of the States, and votes or statements in the international organizations or international conventions. Therefore, it can be summarized that the formation of CIL is the process in which extensive and various kinds of state practice become general practice, simultaneously accompanied by opinio juris. Compared with the current formation theory of CIL, the traditional one has difference in limiting the scope of state practice, as the foundation for the formation of CIL, to the actual activities of states. However, still based on paragraph 1 (b), article 38 of the Statute of the I.C.J. stipulating the two elements are required for the formation of CIL, there is no differences between the current theory and the traditional one. Contrastingly, compared with the new formation theory, the fact in the current theory that resolutions of international organizations or conventions contribute to the formation is in line with the new theory, but on the other hand, the fact that there can be no formation of CIL only with opinio juris without the review on state practice is rather different from the new theory. With the new trend of various forms of state practice from actual activities to verbal acts, current CIL is more likely to be formed based on purposeful, intentional and collective interactions among states, rather than based on natural and individual interactions among them. In other words, there is a high possibility that CIL is emerged from treaties and resolutions, because treaties and resolutions came to be regarded as a part of state practice with the distinguishing development - both in quality and quantity - of the treaties and international organizations after World War II. A set of criteria for the possibility of the formation of CIL based on treaties and resolutions can be deduced from the rulings of international courts. Analysing rulings of international courts, a set of criteria for the formation based on treaties can be found in the North Sea Continental Shelf case of the I.C.J.: the treaty or its stipulation must be a norm-creating; participation of states in the treaty and its stipulation must be broad and representative; and there must be opinio juris as general international law. In addition, a set of criteria for the formation based on resolutions can be acknowledged in the Nicaragua case of the I.C.J. and some awards of arbitration on nationalization: the resolution must be normative; there must be general support from states for the resolution; there must be state practices out of the resolution. Judging from these criteria, it is not so likely that CIL is formed based on treaties and resolutions. Because as for treaties, a majority of treaties subject to the characteristic of jus dispositivum and due to their possible reservations many treaties are not counted as a potential state practice in the formation of CIL, and finally, additional opinio juris not only as a treaty but also as general international law is required, the formation of CIL cannot be guaranteed only with extensive and comprehensive participation of states. Also, as for the resolutions, the reason is that except for the normative characteristic, the general support, there must be additional state practice which is distinguished from the resolution itself. Especially, the requirement for the additional state practice shows that the international court does not accept the assertion that CIL can be formed only with the resolutions of international organizations. Therefore, even though current CIL seems to be formed fast due to the trend of expanding scope of state practice and the purposeful, intentional and collective interactions among states, extensive and comprehensive participation of states in a treaty or a resolution cannot automatically guarantee the formation of CIL. In conclusion, one of the basic characteristics in the current formation of CIL is that CIL can be established relatively fast in order to adjust to the changing international society and international law, especially by the use of the various forms of state practice and the widespread participation of states. This reflects CIL of current time is created in a more flexible way compared with traditional one and is the result of active interactions among sources of international law. Especially, this is a remarkable phenomenon that CIL can be formed from treaties which are another distinct source of international law and resolutions which are not binding. Nevertheless, it cannot be neglected that a traditional boundary among the sources of law is not yet destroyed. Because CIL is not automatically formed by way of widespread participation in a treaty and general support for a resolution. Therefore, it comes to a conclusion that although the current formation of CIL is distinguished from traditional one, CIL still remains 'customary.'