One of the most difficult problems in the study of international law is determining when a rule of law applies to a given situation. This problem has two dimensions: (1) determining what the rule of law is and (2) determining when and how it is applied. The first di- mension, though complex, is the subject of Article 38 of the Statute of the International Court of Justice,’ and the starting point for most dis- cussions of international law.2 Though it may be difficult to establish the existence of a rule of international law, particularly in the absence of a treaty, the process of demonstrating customary international law is one with which international lawyers are familiar.
