The Obligation to Extradite or Prosecute. Clarifying its Nature

The obligation to extradite or prosecute is enshrined in numerous treaties, and it is now the subject of particular attention. On the agenda of the International Law Commission (ILC), it is also at the heart of the dispute brought by Belgium against Senegal before the International Court of Justice (ICJ). State practice and the debates both before the ILC and ICJ show that the non-treaty based status of the obligation remains unclear. This article elucidates such a status and clarifies the definition and scope of this obligation. The article is divided into two parts: in the first, the author concludes that a customary status may be ascribed to the obligation to extradite or prosecute for core international crimes such as genocide, crimes against humanity and war crimes. This status is asserted on the basis of an analysis of the two traditional components of customary law, state practice and opinio juris, a particular attention being paid to state declarations. The second part of the article offers some suggestions with respect to the content of this customary obligation to extradite or prosecute. These suggestions are founded upon several elements, especially, the particular nature of the crimes with respect to which the customary obligation is claimed to exist.