Custom lives! It may not be the jurisprudential “king of all,” as Pindar wrote, but customary law remains a key source of obligation, even in “modern” and “mature” legal systems. One has to know, however, where to find the subtle evidences of unofficial and unenacted norms, and a large part of this book has been an exposition of the role of customary law in contemporary doctrinal debates in various domestic polities, as well as in international law. There remain, however, some lingering questions and nagging concerns as to how custom lives today, its constituent elements, the limits of its applicability, and its ultimate status as a source of law.

False Constraints on Custom

Throughout this volume, some ideas have recurred that, acting singularly or together, purport to place strong limits on the role of custom in law. Most of these are, however, false or misleading, and it is worth summarizing why that is so.