It is largely accepted that the ‘complementarity’ of the ICC vis-à-vis national jurisdictions constitutes one of the key features (if not the key feature) of the Court. Since the beginning of the travaux préparatoires, delegations agreed that, unlike in the system of ad hoc tribunals (based on the ‘primacy’ of their jurisdiction over domestic courts), the ICC should intervene only when the national jurisdictions are ‘unavailable’ or ‘ineffective’ (to use the terminology of the original International Law Commission draft statute). Naturally, the real problem was to shape concretely the way in which the principle of complementarity would operate, and to find the right balance between respect for state sovereignty and effectiveness of the Court's action. The final compromise, mainly reflected in Articles 17 to 20 of the Rome Statute, achieved some important results in seeking this balance. At the same time, it raises a number of substantive and procedural issues that the Court will be called upon to address through its jurisprudence (and, to some extent, has already been facing).

Introduction

When I was asked to take part in this project, it was argued that I have always taken a special interest in the subject of complementarity and the relationship between the International Criminal Court (ICC) and national jurisdictions. This is true. But I am not the only one. We all know that complementarity is a crucial feature of the Rome Statute, which characterizes the ICC with respect to other systems of international criminal justice, and, in particular, the ad hoc tribunals for the former Yugoslavia and Rwanda. It is, one can say, the most distinctive trademark of the ICC. What I continue to think is that the manner in which complementarity is applied and will be applied in the Court's case law will have an effect on the role and authority of the ICC in the years to come. In other words, I believe that the success of the ICC will depend not only on the number of cases referred to it and on how fast and effectively they are handled, but also, and mainly, on how the necessary balance between respect for national sovereignty and repression of the most heinous crimes is achieved.