Over the last 30 years, the UN has shown an unmistakable interest in combating terrorism. This book analyzes the practice of the UN General Assembly and the Security Council in combating terrorism. It answers the question whether these organizations, taking into account their powers and the constitutional and public international law limitations thereof, best contribute to a universal anti-terrorism policy. In order to assess whether both organizations are indeed fulfilling this purpose, the analysis of the adopted counter-terrorism measures of both the General Assembly and the Security Council focuses on their legality and legitimacy. Whereas the measures adopted should clearly fall within the powers of the organizations (legality), testing the legitimacy of these measures adds another layer of information with regard to the quality of these measures. The analysis of the legitimacy of the anti-terrorism measures is based on the theory of Thomas Franck, who claims that a rule's legitim