Hart and Kelsen on International Law

In the recent resurgence of jurisprudential interest in international law, HLA Hart’s theory of law occupies centre stage and doctrinal public international lawyers usually adopt his theoretical vocabulary, in particular his account of the rule of recognition, when they feel the need for some theoretical tools. This is a puzzle because Hart saw philosophy of public international law as peripheral to the main task of jurisprudence—to analyze the ‘distinctive structure of a municipal legal system’—and deemed its study ‘only a relatively small and unimportant part of the most famous and controversial theories of law’. In addition, his own analysis of public international law is widely considered problematic. But while Hart is thought not to have been quite on his game when it came to public international law, it may seem that his is the only game in town when it comes to the place of such law in a general theory of law. I argue that it high time that jurisprudence returned to Kelsen, unhindered by Hart’s distortion of Kelsen’s central ideas, not least because Kelsenian legal theory shows us the benefits of reversing the order of argument about public international law. Instead of, first, constructing a theory of the law of a national legal order and, second, asking whether public international law is law in its light, we should see that understanding the legality of international law illuminates how philosophy of law might productively address some of its central problems. I examine these issues through the lens of the debate about whether the relationship between public international law and national law should be understood as ‘monists’ or as ‘dualists’ urge.

David Dyzenhaus is a University Professor of Law and Philosophy at the University of Toronto, currently a Guggenheim Fellow and a visiting fellow at All Souls. He has just completed The Long Arc of Legality: Hobbes, Kelsen, Hart (Cambridge, forthcoming).