Necessity within the Legal Framework of Self-Defence against Terrorism

This thesis focuses on the criteria established for the use of force in self-defence in international law. The prohibition on the use of force in Article 2(4) of the United Nations Charter is subject to exemption by way of approval from the Security Council, or by invoking the right to self-defence. The use of force in self-defence is promulgated in Article 51 of the United Nations Charter, but is understood to be restricted by the principles of necessity and proportionality. Since the attacks in the United Stated on 11th September 2001, the law on self-defence has focused on the emergence of non-state actors within the framework of jus ad bellum. In view of this, and the contemporary context, this thesis seeks to reappraise the meaning of necessity in light of terrorism. In particular, the study asks whether the meaning of necessity is affected if self-defence is applied against a non-state actor, and if so, how. It also explores the establishment of the two conditions of self-defence, necessity and proportionality, based on the Caroline incident, and examines how the Caroline doctrine has been interpreted in the formulation of rules incorporated in jus ad bellum. The understanding of necessity in self-defence is also re-evaluated by asking the role of necessity in self-defence framework. It is argued that necessity has two important roles in self-defence law. First, it argued that necessity acts as a requirement to self-defence, specifically by seeking whether an armed attack has taken place, and if so, whether there is an alternative option to the use of non-forcible measures. Second, necessity acts as a limitation to self-defence, establishing that any defensive measures must be employed solely to achieve the legitimate aim of self-defence, which is to halt and repel an armed attack. However, it is difficult to assess necessity as a limitation on the use of force in self-defence when force is directed against terrorist groups.