Jus non Scriptum and the Reliance Principle

On the Continent, a general theory of customary law has been developed-what I term the Continental theory; it identifies formation and validity as the central issues in the analysis of custom and customary law. Yet the Continental theory, notwithstanding its longevity and continuing favorable reception among international lawyers, is ridden with problems. In particular, as I argue in the following section, the theory fails for want of a coherent position on the formation issue. In the course of my argument, I suggest a classification of the norms of customary law in terms of a generic category broader in scope than “customary law,” namely “jus non scriptum” or “unwritten law.” No mere refinement of terminology, the broader classification permits a new approach to the troublesome formation issue. I use this classification as a point of departure in the remaining sections of the paper, where, working with a concrete historical example, I develop rudiments of a theory of the formation and validity of unwritten legal norms. The key is the reliance principle, adapted to contexts of unwritten law. I provide an analytical statement of the principle and show that it explains the acquisition of rights and the imposition of duties in some contexts of unwritten law, while avoiding the problems of the Continental theory.