Pacifism and realism both presuppose an unbridgeable gap between war and morality. The pacifist, abhorring the suffering caused by violence, concludes that war is the consummate evil and rejects it under any circumstances. The realist, beginning from a similar assessment regarding the evil of war, concludes that those who bring war on a peaceful nation deserve all the maledictions its people can pour out. These views reflect the negative duty not intentionally to harm innocent persons, on one hand, and the positive obligation that innocent persons be protected, on the other. The pacifist views the prohibition against harming others as more fundamental; the realist accepts the positive duty to protect others as more basic. Historically, the just war tradition has provided an alternative to these extremes. Recent events in the conduct of wars around the world have, however, called into question the relevancy of certain aspects of the just war tradition for modern wars. In this work I critically examine the notion of a just war in terms of both jus ad bellum, or the justifications for going to war, and jus in bello, or the just means of waging war, as it is reflected in international law. I begin with a discussion of various formulations of the realist's and pacifist's positions and argue that the just war tradition provides a reasonable alternative to either of these extremes. I then briefly trace the historical development of the just war tradition beginning with Roman Law. The purpose of this historical analysis is to identify those moral principles and arguments that inspired the development of various aspects of the just war tradition so that these same principles and arguments can be used as a basis for reevaluating existing rules in light of modern tactics and technology. Finally, I expose and discuss serious deficiencies with the way the just war tradition is reflected in current international law and offer proposals for how these problems might be addressed. My conclusion is that the just war tradition can provide effective guidelines for ameliorating the tragedy of war now and into the 21st Century if the issues I identify are adequately addressed.

“Stratospheric Sulfate Injection” (SSI) is an emergent technology that is meant to reduce global warming by blocking incoming sunlight, in particular, by injecting sulfate particles into the stratosphere. Once SSI gets started, it is necessary to keep injecting every 1-2 years; otherwise, the cooling effect will disappear and there will be sudden and potentially catastrophic global warming. Even though the effects are global, SSI can be deployed by a single state or small group of states acting alone and likely would be deployed in this way. There is currently no consensus among lawyers and judges as to whether such “unilateral” deployment of SSI would be legal under international law. The profession therefore requires a comprehensive study of the legal implications of unilateral deployment of SSI. To fill this gap, my thesis asks, “Does unilateral deployment of SSI breach international law?” Examining theories of international law, legal and political philosophy, and the science of SSI, I argue that deploying SSI unilaterally breaches a fundamental jus cogens (“compelling law”) norm of international law: the inherent right of self-defence. This norm entails a prohibition on what I call “perfect capture,” which happens when a foreign state appropriates and permanently monopolizes a domestic state’s responsibility to protect its population. Perfect capture violates the inherent right of self-defence because it represents a state’s renunciation of its capacity to make decisions affecting the survival of its population. Thus, insofar as it constitutes perfect capture, unilateral deployment of SSI grants a single state or small group of states more arbitrary power over the existential conditions of other states than is compatible with the premises of a pluralist international legal order. / Graduate