The just war tradition has been seen as a guiding perspective on the ethics of war since the writings of St. Augustine were rearticulated by Thomas Aquinas. It attempts to provide a framework that validates just conflicts, while at the same time enforcing limits so as to prevent unbridled warfare. Today its fundamental principles can be divided into two broad categories: "jus ad bellum" (no more resorting to war) and "jus in bello" (no more conduct in war). For a war to be just, numerous criteria within these categories must be met. In recent decades, non-state terrorism has become increasingly high profile; indeed, it has dominated the global political agenda in the twenty-first century. It is pertinent, therefore, to ask whether terrorism can be ethically assessed using the Just War tradition. In this essay I will argue that it is possible to ethically evaluate terrorism by employing Just War principles. I will demonstrate that terrorists can satisfy the most important criterion of the Just War tradition. First, they may represent a “legitimate authority” and have “just cause.” Secondly, terrorism can represent a “last resort” and offers a “reasonable prospect of success”. Finally, while many terrorists adhere to the principle of “discrimination,” the concept of “non-combatant immunity” and civil innocence is oversimplified. Furthermore, terrorists may perceive themselves as being in a “supreme emergency,” meaning that the rules of war cease to exist. Terrorism can satisfy the principle of proportionality. However, before I begin my argument, I must establish a working definition of “terrorism”; an important and controversial issue in itself. Walzer describes it as "like rape and murder...an attack on the innocent" (2005......middle of paper......Family Research Council, online accessed: 07/11/2010Roberts, Adams, (1989 ), 'Ethics, terrorism and counter-terrorism', Terrorism and Political Violence 1 (1), pp. 48-70Schmidt Alex P and Jongman Albert I, (1998) 'Political Terrorism' (Amsterdam, Transaction Books) Smilanski, Saul, (2004), 'Terrorism, Justification and Illusion', Ethics, 114, July pp. 790-805Valls, Andrew, (2000), 'Can Terrorism Be Justified', in André Valls (ed.), Ethics in International Affairs, pp. 65-80Walzer, Michael, (1992), 'Just and Unjust Wars: A Moral Argument with Historical Illustrations', (New York: Basic Books)Walzer, Michael, (2005), 'Arguing About War' , (Yale Nota Bene) Wilkins, Burleigh Taylor, (1992), 'Terrorism and Collective Responsibility', (New York: Routledge) US Department of State, (2005), 'National Terrorism Reports', accessible online: 15/11/2010