Adjudication refers to a process for settling disputes, possibly ex aequo et bono but almost always on the basis of international law. It may take the form of resort to arbitration or to judicial settlement. In the case of resort to arbitration, adjudication involves the establishment by the parties of an ad hoc tribunal, and their determination of the law which the arbitral tribunal is to apply (such matters being dealt with in a compromis). In the case of resort to judicial settlement, the dispute is taken to an already-existing judicial body, the statute of which sets out the manner in which it is to operate, including the law which it is to apply. States may agree in advance that a certain class of dispute shall be taken to compulsory adjudication.