Criminal Prohibitions on Membership in Terrorist Organizations

The article analyzes prohibitions on membership in terrorist organizations and examines their justifiability. It begins by providing a definition of a terrorist organization. It then describes the far-reaching modern prohibitions on membership in terrorist organizations in various jurisdictions. The article goes on to provide a doctrinal analysis of membership offenses. Based on similarities with conspiracy doctrine, membership offenses are analyzed as expansions of attempt law or, in some cases, of complicity doctrines. The justifiability of this expansion is examined. The article introduces a distinction between exclusively terrorist organizations, passive membership of which can be legitimately prohibited under certain conditions, and ancillary and dual-purpose organizations, passive membership of which cannot be legitimately prohibited. Next, the justifiability of prohibiting more active forms of membership in each of these types of organizations is discussed. Last, guidelines for the legislation of appropriate prohibitions are proposed.