Traditional and Modern Approaches to Customary International Law: A Reconciliation

Abstract

There are two contemporary approaches to the determination of customary international law: the "traditional," which emphasizes state practice, and the "modern," which emphasizes opinio juris. This article proposes a theory of custom that incorporates both approaches. It rejects analyzing custom on a "sliding scale" in favor of a reflective interpretive approach that reconciles the descriptive and normative justifications for traditional and modern custom.

Keywords: Custom, International law, Customary international law, traditional, modern, descriptive, normative, state practice, opinio juris, Dworkin, Kirgis, Tasioulas, Rawls, Fit, Substance, Sliding scale, Reflective equilibrium