This paper deals with the role of judicial decisions in international adjudication. It is impossible to fail to notice the abundance of prior cases invoked in decisions of international tribunals and that, in order to find out what the law actually is, reference to previous cases is all but inevitable in practice. In some areas of international law, judicial or arbitral decisions have even been said to be the centre of progressive development. Nevertheless, there is an undeniable and deeply-rooted professional trepidation in many parts of the world regarding this enduring phenomenon. Even absent a fully articulated theory of adjudication or legal reasoning, the very idea of “judicial lawmaking” tends to arouse instinctive suspicion, especially when coupled with a denial of any restraining force of prior cases. Be that as it may, observations to the extent that judicial decisions are not veritable sources of international law or only binding between the parties in a particular dispute are only the beginning, and far from the end, of the present inquiry. Several interrelated and intricate questions need to be disentangled and dealt with in order to get a better grasp on what is commonly, and often rather unhelpfully, lumped together loosely under the vague label of “judicial precedent.” The paper is hence partly descriptive and partly revisionary. I do not however intend to rehash general criticisms or defences of precedent. Instead, I aim to present precedent as a general and omnipresent jurisprudential concept that enables and constrains judicial decision-making even in seemingly ordinary cases and to then showcase the specificities of one particular legal system in this respect, namely public international law. Hopefully this provides some of the methodological groundwork for other questions central to the present project, not least concerning the legitimacy of judicial lawmaking.