Rules for Resolving Conflicts of Treaty Obligations of States

Abstract

The growing expansion of international relations and the increasing number of treaties concluded among states, alongside other sources of international law such as customary law, general principles of law, judicial decisions, and peremptory norms, have created conditions in which conflicts between states’ international obligations may arise. A conflict of treaty obligations occurs when the simultaneous implementation of two or more obligations becomes impossible, or when the performance of one obligation necessarily results in the breach of another. Such conflicts typically emerge where treaties share the same subject matter, involve common parties, or impose incompatible legal effects. This study, employing a descriptive–library research method and relying primarily on the law of treaties—particularly the 1969 Vienna Convention on the Law of Treaties—examines the legal rules governing the resolution of conflicts between treaty obligations of states. The findings indicate that international law resolves such conflicts through several established principles, including the supremacy of peremptory norms (jus cogens), the priority of obligations arising under the Charter of the United Nations—especially Article 103—the principle of lex posterior derogat legi priori (later law prevails over earlier law), the principle of lex specialis derogat legi generali (special law prevails over general law), and the principle of harmonious interpretation of obligations. Among these, peremptory norms occupy a superior hierarchical status within the international legal order and render any conflicting treaty or rule void or without legal effect. Similarly, obligations deriving from the United Nations Charter prevail over other international agreements in the event of conflict. With respect to the relationship between treaty law and customary international law, both sources are generally considered equal in normative status unless one of them acquires a peremptory character or gains priority on temporal or substantive grounds. The study concludes that the absence of a centralized legislative authority in the international legal system increases the likelihood of conflicts between states’ obligations. Nevertheless, conflict‑resolution rules play a crucial role in ensuring coherence, legal certainty, and predictability within the international legal order, thereby contributing to the effective implementation of international obligations and the stability of the international community.