Incorporating core crimes under the Rome Statute into domestic legislation : temporal jurisdiction

Implementing the Statute of the International Criminal Court ("Rome Statute") into domestic law has been approached in many jurisdictions using the standard model of transposition. As the Rome Statute contains definitions of serious international crimes, including crimes against humanity, war crimes and genocide, once transposed, those definitions become part of the domestic legal order. The nullum crimen sine lege principle indicates that the national incorporation of those crimes should be prospective. This has been interpreted to mean that domestic jurisdiction should be granted from the commencement date of the implementing legislation or, at the earliest, the date of the State's accession to the Rome Statue. This article argues that such an approach is inadequate due to the earlier criminalisation of the core crimes under treaty and, in particular, customary international law. As a consequence, earlier commencement dates are appropriate for each of the core crimes and do not breach the nullum crimen principle.