The International Court of Justice, considered the principal judicial organ of the United Nations, has consistently, in the peaceful settlement of international legal disputes between states, adopted decisions in the form of contentious judgments and, in response to legal questions posed by competent bodies, decisions in the form of advisory opinions. In this way, it plays a very important role in the peaceful settlement of disputes and the development of international law. However, in international law, no panel has legislative authority, and ambiguities have always arisen regarding the Court's approach to legal lacunae and the mechanism for enforcing its decisions. The main question of the present research is: What is the nature of the different types of decisions of the International Court of Justice, what tools does this court use when facing legal lacunae, and what is the overall mechanism for enforcing its decisions? The authors have used a descriptive-analytical method with the aim of finding a reasonable and documented answer based on international legal regulations. The general results of the research emphasize that while analyzing the nature of different types of decisions of the International Court of Justice from the perspective of their binding force, argue that the Court's practice when facing legal lacunae in issuing contentious judgments and advisory opinions is completely different, and international law has a coherent mechanism for enforcing these decisions.