University of New South Wales Faculty of Law Research Series
Last Updated: 16 February 2013
What is Terrorism? Assessing Domestic Legal Definitions
Keiran Hardy, University of New South Wales
George Williams, University of New South Wales
This paper is available for download at Available at
This paper was published in 16 UCLA J. INT‘L L. & FOR. AFF. 77 (2011). This paper may also be referenced as  UNSWLRS 16.
Anti-terrorism powers were largely enacted as an emergency response to September 11 and later terrorist attacks, and yet they now appear to be a permanent feature of domestic law. How governments apply these anti-terrorism powers depends upon the scope of statutory definitions of terrorism. This article develops three key criteria for assessing the appropriateness of definitions of terrorism in domestic legislation. The first two criteria relate to the principle of legality. They require definitions of terrorism to be drafted in language which (1) gives reasonable notice of the prohibited conduct, (2) confines the operation of legislation to its intended purposes, and (3) is drafted consistently in comparable jurisdictions. The article then tests seven definitions of terrorism against these three criteria. It focuses on legal definitions of terrorism in the United Kingdom, Canada, Australia, South Africa, New Zealand, India, and the United States. The article not only examines the statutory language used to define terrorism in each jurisdiction, but also examines how these definitions have been applied and interpreted since their enactment. This testing process suggests that much remains to be done to improve the clarity, scope and consistency of definitions of terrorism in domestic legislation.