Principles Concerning Parallel Investigations and Parallel Prosecutions of Core Crimes

This chapter considers the general principles concerning parallel investigations and parallel prosecutions in international criminal justice and examines the impact of premises (circumstances or values) specific to international criminal justice on the validity and content of the said principles. It finds that, in international criminal justice, where multiple criminal justice agencies jointly investigate the same criminal case, parallel investigation is a prerequisite, and there are norms that prioritize the merits of joint investigation over the harms of parallel investigation in the domestic plane and inter-State relations. In addition, with regards to parallel prosecution, although norms for the allocation of jurisdiction are prevalent, their content is influenced by the institutional characteristics of International Criminal Justice Institutions. Although the issue of parallel prosecution is regarded as a problem to be avoided in the same way as in the domestic plane, the “first come, first served” rule is basically appropriate. In other words, in addition to the perspective of the litigation economy of the international community as a whole, it seems to be premised on the demand for speed: the normative premise that the sooner justice is done, the better.