In order to fulfil its internal mandate, it was imperative that the Tribunal had the power to exercise jurisdiction over the crimes alleged to have been committed. Whilst 'Jurisdiction without political will is an ineffectual weapon'; 1 equally, the exercise of political will to prosecute without jurisdictional basis is futile. Jurisdiction is 'the authority by which courts and judicial officers take cognizance of and decide cases.' 2 There were two aspects to this with regard to the International Criminal Tribunal for Former Yugoslavia (ICTY): the authority of the prosecutor to initiate and conduct investigations; and the authority of the court to have cases brought before it. The role and function of the prosecutor is examined in Chapter 8 . This chapter examines the exercise of jurisdiction by the court, the legal basis for the establishment of the ICTY by the Security Council, the assertion of primacy by the ICTY over national courts, and the temporal, territorial, personal, and subject matter jurisdiction set out in the Statute of the Tribunal.
The method of establishment and external mandate of the Tribunal had a number of core implications for jurisdiction. First, the speed with which the Statute was drafted and adopted—the flurry of activity to turn what Cassese termed a 'nebulous idea' into a living reality—meant that there was no room for debate on the technicalities, save for a number of interpretative statements made by members of the Security Council. Second, the drafters of the Statute were keen to avert one of the major criticisms of the Nuremberg and Tokyo tribunals being levelled at the ICTY—that the prosecution of individuals for acts which were illegal only after the fact violated the principle nullem crimen sine lege, nulla poena sine lege (no act is criminal unless it is laid down in law and no act can be punished unless punishment is prescribed by law). 3 Both of these factors together explain