The System of the International Criminal Court: Complementarity in International Criminal Justice

Complementarity, the mechanism that regulates the exercise of the concurrent jurisdiction between the International Criminal Court (ICC) and national courts, constitutes one of the key features of the ICC, if not the cardinal one. As such, it keeps attracting the attention of both scholars and practitioners. In addition to the studies related to the interpretation of the statutory provisions - which leave numerous unanswered questions - complementarity has been object of growing attention in relation to its catalyst effects in fostering States' compliance with their duty to prosecute. The first years of activities of the Court have shown the exceptional character of judicial assessments of complementarity; meanwhile, the relevance of prosecutorial assessments of admissibility has emerged. In this context, the complementary nature of the Court, and its relevance in terms of prosecutorial assessments of admissibility, became evident. Starting from the idea that the Court shall encourage the performance of proceedings at the national level, complementarity has been progressively seen as a tool to strengthen domestic jurisdictions, under the concept of “positive†or “proactive†complementarity. This work explores the multifaceted aspects, meanings and functions assigned to complementarity. While acknowledging that complementarity operates in two dimensions - a strict legal one, related to judicial assessments of admissibility - and a broader one, which attains to the ICC prosecutor's consideration of complementarity when selecting the situations and cases to be brought before the Court, this thesis questions whether complementarity can be associated to capacity building functions, and, more generally, to a Court's direct role in overcoming states' inability and unwillingness to prosecute. Based on a throughout analysis of the legal framework, the drafting history and the ICC practice, this thesis suggests that complementarity is a concrete notion, i.e., the mechanism that regulates the exercise of concurrent jurisdiction between the Court and States. Compared to other mechanisms for the allocation of concurrent jurisdiction, such as primacy, it undoubtedly retains a component that fosters dialogue between the Court and states. However, all initiatives aimed at strengthening states' ability and willingness to investigate and prosecute, undertaken directly by organs of the Court or by other, external actors, do not directly depend on alleged effects of complementarity. It is the very existence of the Court, and the commitment to end impunity for the perpetrators of international crimes of all components of the system of justice created through its establishment, that fosters all these, welcomed, initiatives.