The modern era witnessed a significant growth in the number of international organizations, which reflects the objective progress of world civilization. Inter-State associations are of special interest as permanent formations of States having own and inter-State law. Common legal system should be regarded as integral structure created on the basis of principles and norms established by the inter-State association and limiting (with their consent initially expressed in the constitutive treaty) the sovereignty of national law in determined spheres.

 The article deals with the modern inter-State integration processes, legal relations in the inter-State formations, the principal indicia and structure of their legal systems, the problems of supranational (as a rule) nature of the competence of inter-State organs having powers to adopt imperative decisions for all member States of the association.

 The legal systems thereof correspond to autonomous types of inter-State associations, among which there are: legal systems of Commonwealth as a union of sovereign States coordinating their activities in determined spheres; legal systems of Community — a centralized form of inter-State association assuming the voluntary limitation by member States of their sovereign rights to the union structures; legal systems of Union State — a local union of States on the basis of historical, political, economic, socio-cultural, and ethnographic proximity.