The concept of legitimacy and international law

In recent decades the term ‘legitimacy’ has featured heavily in debates about international law and international institutions. Yet the concept of legitimacy, mercurial as it is, has remained under-scrutinised, leading to confusion and misuse. Rather than seeking to advance a particular conception of what may make international law legitimate, this paper seeks to clarify and complicate how international lawyers understand and use legitimacy as a concept. To begin, the paper distinguishes between legal, moral and social legitimacy. It highlights the different ways in which these three approaches to legitimacy have been used in international law scholarship, while drawing attention to some of their more problematic tendencies. From there, it breaks the concept of legitimacy down into three major components: its object, subject and basis. It argues that the tendency to blur these elements has led to much of the uncertainty and obfuscation in legitimacy debates. Finally, the paper considers how legitimacy may be distinguished from coercion, self-interest and habit. Ultimately, it argues that if treated with sufficient rigour, legitimacy provides a useful analytical concept for international lawyers. In doing so, it aims to encourage and facilitate the participation of international lawyers in broader inter-disciplinary debates about legitimacy.