The legitimate authority of international law, i.e. its ability to generate moral duties of obedience for its subjects whether states, international organisations or individuals, has become a subject of growing interest among international legal scholars and legal theorists over the past fifteen years or so. The initial difficulty most accounts face has to do with the reality of international law itself qua decentralised and non-hierarchical legal order. Stemming from those complexities, a second difficulty pertains to the concept of legal authority itself. This article presents a single concept of legal authority and a set of justifications for the legitimacy of international law that can not only accommodate the complexity of contemporary international law, but also make sense of it in the context of competing claims to legitimacy made over the same people by national, regional and international legal orders. The key to the authority of international law in a pluralist legal order lies, the author argues, in lifting the state veil. This implies focusing on the individual as the ultimate subject of authority in international law. The article’s argument unfolds in three steps. It starts by presenting the conception of legal authority the article is based on, and in particular a revised co-ordination-based version of Joseph Raz’s service conception of authority. It then argues that this autonomy-based account of authority best explains the legitimacy of international law by focusing on four key features of legal authority in the international context: the multiplicity of international subjects and law-makers and their relationship; the role of co-ordination in the justification of international law’s authority; the piecemeal nature of authority and the role of state consent in that context; and, finally, the protection of state sovereignty and its compatibility with the authority of international law. In the third and final section, the article addresses borderline cases, and in particular relativism-based exclusions of international legal authority and exceptions to that authority based on justified international disobedience.
‘The further we depart from the picture of international laws as being created solely by states and as dealing solely with the relations of states to one another — and the more seriously we take the idea that human beings, not states, are the ultimate objects of moral concern — the clearer it becomes that a satisfactory account of the legitimacy of international law must include more than an explanation of why States ought to regard the international institutions through which law is made as having the right to rule. More precisely, appreciating the new face of international law shows just how inadequate the traditional framing of the question of the legitimacy of international law is. The question is much broader than “Why should states consider international law binding?”