We start this chapter with a description of some of the features of the sources of international law that may complicate an examination of conflict of norms in public international law. We then ask whether there are any a priori hierarchies in international law and, thereafter, examine the principal sources of international law as they may play out in a conflict of norms. We conclude the chapter by redefining international law as constituted by, first, general international law and, second, particular international law.

The continuing uncertainty as to the sources of international law

The problem of identifying the sources of international law

It is generally recognised that norms of international law may derive from the following five sources: treaties; custom; general principles of law; unilateral acts of states; and acts of international organisations. Obviously, a distinction must be made between these five ‘sources’ of law and the infinite number of ‘norms’ they may produce.

The first three of these sources – treaties, customary law and general principles of law – are explicitly confirmed in Art. 38(1)(a)–(c) of the ICJ Statute as part of the ‘applicable law’ before the ICJ.