This book casts new light on the application of the principle of proportionality in international law. Proportionality is claimed to play a central role in governing the exercise of public power in international law and has been presented as the ‘ultimate rule of law’. It has also been the subject of fierce criticism: it is argued that it leads to unreflexive and arbitrary application of the law and deprives rights of their role as a ’firewall’ protecting individuals. But the debate on proportionality has tended to focus on the question of ‘how’ proportionality should be carried out. Much less attention has been devoted to the question of ‘who’.

This edited volume bring together scholars from a wide range of areas of international law to consider that question: whose interests are at stake when courts and other legal authorities apply the principle of proportionality? In so doing, this volume casts new light on the role which proportionality can play in international law, in shaping and modulating the power relations between the different entities governed by it.