Introduction

What is the character of international law as a legal system? How different is international law from municipal law? Is this difference significant or is it made into more than is justified? What consequences flow from international law being a distinct legal system in terms of its practice and prospects?

International law as a discipline has exhibited an unusual propensity to ask such questions, perhaps because, historically and politically, this has often seemed less a matter of course than for domestic legal orders. In truth the debate about international law as law covers three distinct though related questions. The first deals with what type of legal system international law is. It is immediately quite clear that international law operates differently from domestic law. But to what extent is it a sui generis legal system? Second is the rather more ominous question of whether, on the basis of its defining characteristics, international law can even qualify as ‘law’ properly so called. Confronted with widely publicised and spectacular violations of international law, popular opinion is often tempted to give up on the idea, yet international law is routinely treated as law by its practitioners. Why this disjunction? Third, one of the difficulties in determining what sort of law international law is, or whether it is law at all, is that it is a constantly evolving legal system that has seemingly taken many different shapes over time. Is international law so changeable that it lacks the minimum stability a legal order should have, or is it instead remarkably constant over time despite the appearance of constant renewal?