The Prosecutor of the International Criminal Court is the first prosecutor of a permanent international criminal court and is responsible for investigating situations where international crimes appear having been committed and for prosecuting perpetrators of these crimes before the Court. The traditional contrast between those systems applying the principle of mandatory prosecution and those applying the discretionary principle, raised the question on the applicable model in the international criminal justice system. The traditional selectivity characterizing International Criminal Law, the limited resources, and the tendential use of procedural mechanisms familiar to common law systems before international criminal tribunals are some of the reasons leading scholars to attribute discretion to the Prosecutor of the International Criminal Court as well. The purpose of this book is to determine whether the Prosecutor effectively enjoys discretion and possibly to what extent. The statutory framework does not necessarily point towards a strong discretionary power of the Prosecutor, and practice reveals that the discretion granted to the Prosecutor in recent years seems sometimes to have jeopardized the effectiveness of his activities.