ABSTRACT
The surprise decision by the Special Tribunal for Lebanon that transnational terrorism is a customary international law crime1 sparked considerable controversy in 2011. Until then there was a widespread belief that there existed neither an agreed definition nor an international crime of terrorism. For many, the decision did not change that long-held belief, because of the unsatisfactory nature of the Tribunal’s reasoning about customary law. This chapter first outlines how international law dealt with terrorism in a criminal context up until the decision of the Tribunal in 2011. It then briefly critiques the Tribunal’s assessment of the various material sources (national laws and judicial decisions, international and regional treaties, and United Nations resolutions) purportedly evidencing a customary international law crime of transnational terrorism.2 That critique demonstrates that even on the Tribunal’s own criteria for identifying customary law, there is no international crime of terrorism.
