ERNEST PETRIČ CYIL 7 ȍ2016Ȏ in international law, and specifically to Articles 53 and 64 of the VCLT of 1969, 6 which were later recapitulated also in the Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations of 1986. 7 First, it should be noted that it is evident from the analysis of travaux preparatoires of Article 53 of the VCLT and the discussions held at the Vienna Conference of 1969, 8 which adopted the wording of the Convention as subsequently ratified by States, and which has today, grosso modo , already become customary international law, that despite a fairly wide variety of views expressed initially by the members of the Commission for International Law and later also by the representatives of States at the Conference, the fundamental reason for the inclusion of this article in the Convention was evidently the prevailing view that, in principle, when concluding treaties the will of States cannot be free and unlimited, as is otherwise the case in international law. In fact, it is limited by certain fundamental norms and principles, by “ jus cogens ”. What limits the free will of States when concluding treaties ( jus contrahendi ), with other words, where this exceptionality of jus cogens that limits the sovereign will of States when concluding or amending treaties originates from, and what exactly jus cogens is are by all means questions that need to be touched on before we try to answer the question of whether fundamental principles of the UN Charter can also be classified as norms and principles of jus cogens . Whether there are norms and principles in international law which are beyond what the will of States can decide on is an old question that has been present in the international legal theory for centuries. In other words, whether international law is only the expression of the will of States conveyed in the formal sources of international law, indisputably defined in Article 38 of the Statute of the ICJ, or whether the will of States, especially when concluding treaties but also when creating customary international law, through their actual conduct, is nevertheless limited is the core problem of jus cogens . In the legal theory, the representatives of explicit positivism have denied the existence of jus cogens , while the representatives of natural law schools on international law in particular have substantiated its existence with arguments running the gamut from the idea of “God’s law” to various arguments seeking the answer to the question of what it is that limits the will of States as some higher law, i.e. jus cogens . Article 53 of the VCLT sine dubio introduces jus cogens into international law as a special legal category. There are no clear and uniform answers to a number of questions regarding jus cogens either in the wording of the text of the mentioned 6 Vienna Convention on the Law of Treaties, 1155 UNTS 331. 7 Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations (not yet entered into force). 8 On Article 53 of the VCLT see particularly K. Schmalenbach, Commentary to Art. 53 of the Vienna on the Law of Treaties of 1969, in: O. DÖRR, K. SCHMALENBACH (ed.), Vienna Convention on the Law of Treaties: a Commentary , Berlin 2012.