Introduction

I recall first studying international law at law school in the mid-1990s. The course I took was taught by a disciple, and former student, of Judge Rosalyn Higgins. As well as to educate, the course's basic objective was to convince young lawyers of the relevance and importance of international law, despite the apparent vagaries and shortcomings of the international legal system.

We are all familiar with the standard critique such an approach sought to address: the critique led by legal positivists such as John Austin that laws properly so called are a species of commands which flow from a determinate source and are enforced by effective sanctions: as in developed domestic legal systems. On this analysis, international law was not law at all, but a mere elaboration of the international morality of State conduct. And even this morality was of limited effect; as States do not, in practice, invoke international law save in the service of their own interests. On this view, international law is merely a tool used in the course of international diplomacy.

We are all also familiar with the standard ‘policy-science’ riposte, championed by such luminaries as Professor Louis Henkin and Judge Higgins herself. This was that legal positivists ask themselves the wrong questions. What matters is not whether the international legal system has analogues to domestic legal systems of legislative, judicial, or executive branches, but whether international law is reflected in the policies of nations and in relations between nations.