Defining terrorism: one size fits all?

This article challenges the idea, both in domestic and international law, of defining terrorism. Using section 1 of the UK's Terrorism Act 2000 as an illustrative example, this article argues that a single definition of terrorism is invariably broad owing to the need to accommodate the lowest common denominator. This is damaging to the ‘principle of legality’ as recognized in British public law and the ECHR. Moreover, this problem is further exacerbated by the increasing application of counterterrorism legislation to non-international armed conflicts. This article therefore suggests an alternative solution: multiple definitions of terrorism whose breadth is dependent upon the specific circumstances for which they are designed. Fears that such an approach may amount to an ‘expression of inconsistency’ will be addressed by arguing that law's capacity to shape and frame public and political debate on the concept of terrorism is over-exaggerated. Legal definitions of terrorism therefore should remain primarily concerned with the legal rather than political function of defining terrorism.