Almost twenty-five years have passed since the adoption of the Constitution of Ukraine, but during this time the legislator has not made the necessary changes and additions to Article 9 of this regulatory legal act. This article of the Constitution regulates the issue of the place of an international treaty in the legal system of Ukraine, however, this regulation is imperfect and in practice gives rise to a number of conflicts. In particular, according to Article 9 of the Constitution of Ukraine, only those international treaties of Ukraine are recognized as part of the national legislation of Ukraine, the consent to the binding of which is provided by the Verkhovna Rada of Ukraine. Thus, the place of intergovernmental and interdepartmental international treaties in the system of sources of law of Ukraine is uncertain, and therefore the rules for their application are not regulated. In addition, the question of the ratio of the norms of the aforementioned international treaties with the norms of the Law of Ukraine remains unanswered. The supreme body of the judiciary of Ukraine proposed ways to overcome these problems, but they are not sufficiently reasoned. Despite this, another long-standing problem of Ukrainian law is the problem of determining the rules for the operation of international customs in Ukraine. A number of modern examples of the application of international custom to the regulation of public relations in Ukraine demonstrate to us an urgent need to formulate a detailed legislative regulation of this issue. For example, we are talking about numerous cases of citizens of Ukraine appealing to domestic courts with claims against the Russian Federation, as a result of which, despite the principle of state jurisdictional immunity enshrined in Ukrainian legislation, not only civil proceedings begin, but even claims are satisfied. The basis for this is a number of decisions of the European Court of Human Rights (for example, the decision in the case "Oleinikov v. Russia"), which states that the provisions of the United Nations Convention on Jurisdictional Immunities of States and Their Property 2004 and the European (Basel) Convention on State Immunity 1972 can be applied as international custom. So, an interesting legal incident has developed in Ukraine: in the absence of legislative regulation of the issue of the place of international custom in the legal system of Ukraine, domestic courts turn to it on the basis of decisions of the ECHR, which, according to Ukrainian legislation, is the source of Ukrainian law. At the same time, individual rules for the operation of the customs of international humanitarian law in Ukraine were regulated at the level of a subordinate normative legal act - a special Instruction approved by the Ministry of Defense of Ukraine. By adopting it, the legislator implemented the basic norms, including the usual ones, of international humanitarian law, which should have greatly facilitated the procedure for their application by Ukrainian military personnel. However, the Instruction does not reflect certain customary norms of international humanitarian law quite correctly, which can cause serious problems in practice. In addition, the legally not precisely formulated Art. 483 of the 2001 Criminal Code of Ukraine, which provides for liability only for violation of the laws and customs of war stipulated by international treaties, the consent to be bound by which was provided by the Verkhovna Rada of Ukraine, but not by international customs, of which there are quite a few in this area.