In the preceding chapters I have sketched the essential outlines of a new theory of customary international law. I have demonstrated that this theory not only helps to resolve many of the conceptual and practical enigmas of traditional legal doctrine, but also can be applied to particular contemporary disputes about the content of customary international law across a wide range of subject areas, including international tax law and international human rights law. It is helpful now to step back and evaluate the strengths of this theory, some potential critiques of it, how far it departs from existing theory, and its implications for how customary international law can and should evolve.

STRENGTHS OF THE THEORY

As to strengths, the theory articulated here satisfies all of the criteria for an effective theory of customary international law that I set out in Chapter 1. It offers a normative background framework for evaluating the status of particular norms as customary law. In particular, it grounds this evaluation in fundamental ethical principles and develops, based on these principles, a sophisticated methodology for determining the content of customary international law.

By contrast, the International Court of Justice (ICJ) in its decisions has too often avoided such a transparent normative methodology and instead resorted to blunt declarations that a particular norm is or is not a norm of customary international law. It is clear that the Court in making these declarations is presupposing certain normative premises, but it often does not adequately disclose them.