Introduction

The emergence of specialised and autonomous rules, legal institutions and spheres of legal practice has been described as resulting in the 'fragmentation' of international law. The International Law Commission (ILC) has addressed this issue in a comprehensive report, which offers, in the words of one of its authors 'a theoretical construct and a set of practical techniques aimed at harmonising the disparate parts of international law'. A key aspect of the ILC report was the role of Article 31(3)(c) of the Vienna Convention on the Law of Treaties, as the expression of the principle of ...