This book analyzes the position of the ICC in relation to national court systems. The research illustrates that what seemed to be a straight forward relationship between the ICC and national courts under the complementarity mechanism, proves to be much more complex in practice. Using the referrals of Uganda and Darfur, the book demonstrates ways in which it might be possible to prosecute for crimes currently not prosecuted by the ICC and brings to light possible solutions to overcome the gaps in law and practice in the jurisdictional relation between the ICC and national systems. It will be of value to academics, students and policy-makers working in the area of international law, international organizations, and human rights.