This study examines the different functions of international courts and tribunals. The question is whether international courts and tribunals do, in fact, perform a multiplicity of judicial functions and, if so, how these judi­cial functions are shaped in practice. A selection of cases from the International Court of Justice (ICJ), the International Tribunal for the Law of the Sea (ITLOS) and the Appellate Body of the World Trade Organization (WTOAB) is subjected to a systematic analysis.