ABSTRACT
This chapter investigates the empirical research and theory in international relations dealing with notions of just war theory and political power. Just war theory is useful for explaining preemptive and preventive use of force. Just war theory was developed over the span of many centuries, from a variety of Catholic theologians, including St. Augustine of Hippo, St. Thomas Aquinas, and Grotius to Jean Bethke Elstain, Douglas Lackey, Paul Ramsey, and Michael Walzer. The most explicit references to just war theory are likely to come from Roman Catholic sources, but implicit references to its arguments may arise from anywhere because of the way in which it has become incorporated into Western thought. The result has been a rich conceptual framework that allows one to examine the primary phases of war: jus ad bellum, jus in bello, and jus post bellum. Jus ad bellum requirements revolve around five principal elements: just cause, right intention, legitimate authority, last resort, and likelihood of success.
