The Concept of an International Organization in International Law

Abstract

Despite their exponential growth in number and activities, international law lacks a comprehensive legal concept of an international organization. The book tackles this topic from the perspective of the legal nature of the legal systems developed by international organizations. It is the first comprehensive study of the different concepts under which international organizations’ legal systems are commonly understood: functionalism, constitutionalism, exceptionalism, informalism. It has a threefold purpose: to trace the historical origins of the different concepts of an international organization, to describe four families under which these different notions are subsumed, and to propose a theory which defines international organizations as ‘dual entities’. The concept of an international organization is defined looking at the nature of the legal systems they develop. The notion of ‘dual legal nature’ describes how organizations create particular legal systems that derive from international law. This peculiar condition affects the law they produce, which is international and internal at the same time. This conceptualization allows the development of a common legal framework applicable to all international organizations, despite their differences in terms of powers, membership, size, and other descriptive features. In particular, the most valuable consequence of this conceptualization is to rebut a frequent argumentative motif, under which organizations are either perceived as vehicles for member states’ interests or as autonomous entities. The effects of the dual legal nature are discussed, analysing international responsibility, the law of treaties, and the validity of organizations’ acts.