Introduction

For a long time, there has been a disconnection between international and domestic justice. International and domestic justice have been treated as two autonomous systems, like ying and yang. Today, the two systems work increasingly in tandem. This is largely the result of the principle of complementarity which is one of the cornerstones of the architecture of the Rome Statute of the International Criminal Court (ICC).

Complementarity is formally an organizing principle for the regulation of concurrent jurisdiction under the Rome Statute. But it has far broader implications. It shapes various dimensions of ICC and domestic practice, ranging from prosecutorial strategy and criminal policy to statutory implementation and compliance. It is of fundamental importance for the long-term success of the contemporary system of international justice.

In the past years, complementarity has witnessed a dynamic development in practice, inside and outside the Court. Within the ICC, each organ has sought to put its own ‘stamp’ on complementarity. The Office of the Prosecutor has developed guidelines and policy principles on complementarity. Other aspects have been addressed by the jurisprudence of the Court or approaches of the Registry