HUMANITARIAN INTERVENTION AND PRETEXTS FOR WAR: A long-standing objection to legalizing unilateral humanitarian intervention is that states would use a humanitarian pretext to initiate aggressive wars, with a consequent increase in the number of such wars. The article discredits the objection by drawing primarily on two research programs: quantitative analyses of the correlates of war, and qualitative analyses of the unintended political constraints that result from states' efforts to legitimate military aggression. The article concludes that lifting the prohibition on unilateral humanitarian intervention would be equally, if not more, likely to reduce the aggregate number of wars by aggressor states.

The legal status of humanitarian intervention poses a profound challenge to the future of global order. 1 The central question is easy to formulate but notoriously difficult to answer: Should international law permit states to intervene militarily to stop a genocide or comparable atrocity without Security Council authorization? That question has acquired even greater significance in the wake of military interventions in Kosovo and Iraq, and nonintervention in the Sudan. Concerted deliberation on these issues, however, has reached an impasse. A key obstacle to legalizing unilateral humanitarian intervention (UHI) 2 is the overriding concern that states would use the pretext of humanitarian intervention to wage wars for ulterior motives. In this article, I argue that it is just as likely, or even more likely, that the impact on states would be the opposite. Drawing on recent empirical studies, I contend that legalizing UHI should in important respects discourage wars with ulterior motives, and I discuss changes to international legal institutions that would amplify that potential effect. The concern that states would exploit a humanitarian exception to justify military aggression has long dominated academic and governmental debates. This concern pits the virtues of humanitarian rescue against the horror of having expanded opportunities for aggressive war. Dating back to Grotius, proponents of legalizing humanitarian intervention have struggled with the objection that their proposals would be abused as a pretext for war. 3 The proponents were most influential in the late nineteenth century 4 -- admittedly a period in which international law permitted ...