States are obliged under treaties such as the Genocide Convention, the Geneva Conventions and the Torture Convention to enact legislation that gives effect in national criminal law to prohibitons in the treaties. The law and practice of international criminal jurisdictions provide that it is significant whether national prosecutions for conduct amounting to genocide, crimes against humanity and war crimes can use the characterization of international crimes and not just ordinary crimes (such as murder). Several states have already imported these international crimes into national criminal law - for example, Canada and Germany. This publication is based on presentations made at a seminar organized by the Forum for International Criminal and Humanitarian Law (FICHL) on 27 October 2006 focused on particular challenges in the process to import such crimes into national law.