A Reflexive Concept of Law: International Law’s Legality

A talk in the John Austin Seminar Series Speaker: Prof Shun Kaku (Waseda Univeristy, Faculty of Law) Chair: Prof George Letsas, Professor of Philosophy of Law (UCL Laws) About the Seminar: The paper proposes a reflexive concept of law to resolve the long-standing legal-philosophical question of whether international law is law. Many legal philosophers, including HLA Hart, have doubted its legality or treated it as a marginal instance, even though most international lawyers regard it as law. Arguably, this dismissive attitude among legal philosophers rests on the legal positivist assumption that the parallel question of what law is is purely theoretical and can be answered in a descriptive, or non-evaluative, way. However, given that law can be law because it is treated as such in its interpretive practice, and, more broadly, social practice, it must be explained why the practice of international lawyers can be disregarded. Ronald Dworkin’s interpretivism appears to offer a more practice-oriented approach to the question of the legality of international law by treating it as a doctrinal question. However, his posthumous article highlights dissimilarities, rather than similarities, between international law and (domestic) law, as what founds the legitimacy of international law is not associative obligation in the political community, but the duty of mitigation. The paper defends interpretivism and argues that any answer to the question of whether international law is law must be defended as a claim within an interpretive practice of law in domestic society. Conversely, the legality of the law of each domestic society may also be assessed within the interpretive practice of international law. International law and domestic law together form a web of laws that acknowledge each other as laws. In this mutual, or reflexive, relationship, laws have in common an aspiration for the rule of law, or, in Lon Fuller’s terms, the inner morality of law. About the Speaker: Shun Kaku is Professor of Legal Philosophy at the Faculty of Law, Waseda University, Tokyo, and a Visiting Fellow at Clare Hall, the University of Cambridge. After completing an undergraduate law degree at the University of Tokyo, and before completing his PhD in legal philosophy at the University of Tokyo, he served as a Research Associate at the University of Tokyo, and then an Associate Professor at Hokkaido University. He was a Visiting Fellow at the Lauterpacht Centre for International Law, the University of Cambridge, a Visiting Researcher at the Max Planck Institute for Comparative Public Law and International Law, and a Special Research Fellow of the Alexander von Humboldt Foundation. Professor Kaku works primarily in the areas of legal philosophy and international law. He is especially interested in the concept of law, the relationship between law and morality, and the normative foundations of international law, and examines them from the perspective of participants in the plurality of practices of law, which stand side by side with and mutually recognise one another as an endeavour aspiring to the rule of law. Developing this idea, he is currently working on publishing a book in English theorising the reflexive concept of law. Apart from writing numerous articles and book chapters, he is the author of Reclaiming the Philosophy of International Law (2022, in Japanese), an award-winning book from the Japanese Association of Legal Philosophy, and a coeditor of several books. He teaches broad areas of legal philosophy, including issues of global justice and the global legal order, at graduate and undergraduate levels. Image by Getty Images on Unsplash