Article 90 of the Constitution of Poland (the constitutional law) is defined not only in the jurisprudence, but also in the doctrine, as the legal basis for the accession of a member state (including Poland) to an international organization. This participation is primarily related to membership rights, but also to obligations. Among the former, it is necessary to point out, firstly, reaping the benefits of membership in an international organization, secondly, exercising all statutory and customary membership rights, or participation in the decision-making process. On the other hand, member duties include, first of all, the performance of statutory obligations, supporting an international organization in achieving organizational goals and functions, or solidarity with the organization and its member states.