Legal commentators have not always considered advisory opinions as a legitimate judicial function. Under both national and international law, it is often considered that only ripe controversies can be legitimately decided by a court of law. Under international law, advisory opinions are also criticized for undermining sovereignty when consent is not obtained from all states affected by the matter. By examining the International Court of Justice’s (ICJ) advisory opinions in light of comparative law, the author argues that this criticism underestimates the evolution of the judicial function, as much in international as in national law. The advisory opinion is a mode of social ordering that stands somewhere between consultation and adjudication. The advisory opinion not only adopts most of adjudication’s characteristics but abo has the added flexibility of consultation because it can consider a wider spectrum of opinions than can adversary procedures. The ICJ’s advisory opinions can almost be assimilated to adjudication. Considering that they have also greatly contributed to the development of international law, the ICJ’s advisory opinions remain an integral and legitimate part of the court’s judicial function.