Papers originally presented in a conference held at the Catholic University, Milan, on 10-11 May 2002.

This work comprehensively analyses the suitability of existing international legal tools to enforce rules prohibiting terrorism. Contributions from leading experts in international law examine questions relating to the proper role of international law in combating terrorism.

In Peremptory Norms of International Law and Terrorism (Jus Cogens) and the Prohibition of Terrorism, Aniel de Beer evaluates the role of peremptory norms of international law or jus cogens in the fight against terrorism.

In this paper, Michael Schmitt explores the legality of the attacks against Al Qaeda and the Taliban under the "jus ad bellum," that component of international law that governs when a State may resort to force as an instrument of national policy. Although States have conducted military counterterrorist operations in the past, the scale and scope of Operation Enduring Freedom may signal a sea change in strategies to defend against terrorism. This paper explores the normative limit on counterterrorist operations. Specifically, under what circumstances can a victim State react forcibly to an act of terrorism? Against whom? When? With what degree of severity? And for how long? The author contends that the attacks against Al Qaeda were legitimate exercises of the rights of individual and collective defense. They were necessary and proportional, and once the Taliban refused to comply with U.S. and United Nations demands to turn over the terrorists located in Afghanistan, it was legally appropriate for coalition forces to enter the country for the purpose of ending the ongoing Al Qaeda terrorist campaign. However, the attacks on the Taliban were less well grounded in traditional understandings of international law. Although the Taliban were clearly in violation of their legal obligation not to allow their territory to be used as a terrorist sanctuary, the author suggests that the degree and nature of the relationship between the Taliban and Al Qaeda may not have been such that the September 11 attacks could be attributed to the Taliban, thereby disallowing strikes against them in self-defense under traditional understandings of international law. Were the attacks, therefore, illegal? Not necessarily. Over the past half-century the international community's understanding of the international law governing the use of force by States has been continuously evolving. The author presents criteria likely to drive future assessments of the legality of counterterrorist operatio7.

Now available as an eBook for the first time, this 2006 book from the Melland Schill series considers the main legal issues concerning the use of force by international organisations and states. It assesses the achievements and failures of the United Nations' collective security system, and discusses the prospects ahead. It also deals with the use of force by states in self-defence and on other legal grounds. The book discusses to what extent the rules on the use of force have evolved since the end of the Cold War in order to meet the needs of the international community. It focuses in particular on the military operations directed against terrorism and weapons of mass destruction. The research is developed from the standpoint of the sources of international law. It rejects a static vision of the rules on the use of force, including those enshrined in the UN Charter. Rather, it highlights the interaction between conventional and customary international law and the exposure of both sources to state practice.

Includes annex: The Huelva Declaration for an Alliance of Civilizations against Terrorism.

Government responses to terrorism can conflict with the protection of human rights and the rule of law. By comprehensively looking at all aspects of counter-terrorism measures from a comparative perspective, this book identifies best practices and makes clear recommendations for the future.