ABSTRACT
The increasing incidence and impact of acts of political terrorism over the last twenty-five years have demonstrated that independent, national attempts to deal with the problem are not adequate. External support for terrorist operations, the possibility of terrorists escaping to safe havens across international boundaries and the switching of targets by terrorists to less wellprotected persons and property abroad as security at home improves are indicators of the transnational nature of much political terrorism. Some rules of international law, like those on territorial sovereignty and non-intervention, have stood in the way of unilateral action by States to pursue and apprehend transnational terrorists. Existing regimes of criminal co-operation have proved inadequate or incomplete to meet the problems posed by terrorism. To some extent also, the deficiencies of the legal response to terrorism are the intrinsic limitations of domestic law: favoured terrorist techniques, like hijacking of aircraft, were not specifically criminal; even where the terrorist activities were embraced by existing criminal offences, those offences were often not extraterritorial, particularly for common law States; even rules of national criminal procedure proved to be substantial handicaps in investigating terrorist offences. States could, and did, take steps by themselves to address these problems but even here, international legal considerations impinged, making difficult or legally dubious some of the responses States wished to make. The rules on criminal legislative jurisdiction under customary international law limited the powers of States to criminalise extraterritorial activity. The law of international human rights was also a restraint on some changes in criminal procedure that States wished to introduce.1
