The international struggle against impunity for perpetrators of atrocities, including genocide, crimes against humanity, and war crimes, has been a key interest of the international community since the end of World War II. Many achievements have been accomplished with respect to international collaboration on the “substantive issues” of international criminal law (ICL), such as defining and criminalizing the core crimes of international law, yet collaboration on the procedural and practical aspects of ICL, known as mutual legal assistance (MLA) has been neglected.