The Justice of War: Its Foundations in Ethics and Natural Law puts normative ethical theory at the forefront in its discussion of the justice of war. Situating the modern theory of just war in its historical context, Richard A. S. Hall gives full attention to natural law, a mainstay of just war theory. Hall considers the American philosopher Josiah Royce’s implicit theory of just war with its suggestion of a fourth component of just war theory (in addition to jus ad bellum, jus in bello, and jus post bellum), namely, jus ad pacem—justice/law for or about peace—concerning the prevention of war and the maintenance of peace. This book addresses, and answers affirmatively, the following questions raised by just war theory: Can just war theory be rationally defended against its realpolitik critics? Can there by such a thing as a just or moral war? The book aims at showing the doubters and critics that just war theory is a viable alternative to both the political realism of realpolitik and pacifism. In brief, war can be morally justified, though under very restrictive conditions.