Vanderbilt Journal of Transnational Law


Anthony D'Amato

First Page



Arthur M. Weisburd's article, "Customary International Law: The Problem of Treaties", focuses on an important problem that has been relatively overlooked: whether current doctrinal scholarship accords too much weight to treaties as constitutive of customary practice. Few issues in international law are more important than the question of where an international rule comes from and how it is proved. Professor Weisburd has addressed a significant component of this basic question. Since he regards me as the leading offender among writers who overdetermine the value of treaties, I would like to take this opportunity to respond.

As a preliminary matter, I must say that I could not be more gratified than to be accused of giving treaties more weight than they deserve as components of the state practice that generates customary international law. When I wrote my book on custom in 1971, publicists of international law generally agreed that the content of treaties was irrelevant to customary law; therefore, treaties deserved no weight at all in the assessment of custom. At that time I could hardly anticipate a day when a writer would worry about giving treaties too much weight.

My great law school teacher, Professor Richard Baxter, summarized the prevailing consensus in a 1961 seminar by proposing that parties enter into treaties either to carve out for themselves a special rule that derogates from the underlying rule of customary international law, or to reaffirm the underlying rule in contractual form. In the former case, the underlying rule of customary law is unaffected, since the parties deliberately derogated from it; in the latter case, the underlying rule remains the same by definition. Hence, why look at treaties at all if the purpose is to discover the general customary rule? The treaty itself can never determine what the general rule is, Professor Baxter concluded, because it is equally likely to derogate from or to affirm the customary rule.