The article is devoted to the issues of the correlation of an international treaty and international custom, their determination and interrelation. Since an international treaty and international custom are the main and most widespread sources of modern international law, the analysis of their correlation is quite relevant. International treaties and international customs are subject to constant application by subjects of international law (states and international organizations), which requires optimization and search for effective mechanisms for improvement in modern international relations, which makes the study of these main sources of international law relevant. The analysis is carried out of the UN General Assembly Resolution A/RES/73/203 of December 20, 2018 “Identification of customary international law”, which is important for the theory and practice of international law, especially for the issues of sources of international law. The results of this study indicate that an international treaty differs from an international custom in its specificity, the peculiarity of the object of legal regulation, the form of consolidation and the significant advantage of treaties in terms of their number in modern international law. An international treaty arises and is formed as a result of negotiations and fruitful work of subjects of international law on rules, mutual rights and obligations on certain issues of cooperation. International treaties have specific names and a clearly established subject of legal regulation. It is noted that international custom is formed as a result of the practice of activities of subjects of international law in the course of the historical process of international relations. The legal nature of international custom is consensual on the part of subjects of international law, primarily states and international organizations.It is concluded that in the process of transition from the emergence of international custom to the adoption of an international treaty, customs help to fill gaps in international law. The reverse process is also possible, when international treaties become widely applicable and take on the character of international custom, for example, international legal treaties in the field of human rights protection, which subsequently become general practice.
Yaroslav Pasichnyk (Sun,) studied this question.