National Implementation of the Complementarity Regime of the Rome Statute of the International Criminal Court: Obligations and Challenges for Domestic Legislation with Nigeria as a Case Study

The thesis is an analysis of how the complementarity regime of the Rome Statute of the International Criminal Court (ICC) can be implemented in member states, specifically focusing on African states and Nigeria. Complementarity is the principle which outlines the primacy of national courts to prosecute a defendant unless a state is ‘unwilling’, ‘genuinely unable to act’, assuming the crime is of a ‘sufficient gravity’ for the ICC. This thesis argues that a mutually inclusive interpretation and application of complementarity should be followed because it will increase domestic prosecutions and reduce self-referrals to the ICC. African states need to have appropriate legal framework in place; implementing legislation and institutional capacity as well as credible judiciaries to investigate and prosecute international crimes. The mutually inclusive interpretation of the principle of complementarity entails that the ICC should provide assistance to states in instituting this framework while being available to fill the gaps until such time as these states meet a defined threshold of institutional preparedness sufficient to acquire domestic prosecution. The minimum complementarity threshold includes proscribing the Rome Statute crimes in domestic criminal law and ensuring the institutional preparedness to conduct complementarity-based prosecution of international crimes. Furthermore, it assists the ICC in ensuring consistency in its interpretation of complementarity. The thesis uses the policy-oriented approach, to define the relationship between the ICC and states as one of interdependence and to demonstrate that decision makers at the domestic level need to join the international community to implement complementarity. Complementarity has been stipulated in the Rome Statute without a clear and comprehensive framework of how states may implement it. The thesis proposes a framework that will hopefully help member states to overcome this problem.