This essay argues that the ethics of humanitarian intervention cannot be readily subsumed by the ethics of just war without due attention to matters of political and moral motivation. In the modern era, a just war draws directly from self-benefitting motives in wars of self-defense, or indirectly in wars that enforce international law or promote the global common good. Humanitarian interventions, in contrast, are intuitively admirable insofar as they are other-regarding. That difference poses a challenge to the casuistry of humanitarian (...) intervention because it makes it difficult to reason by analogy from the case of war to the case of humanitarian intervention. The author develops this point in dialogue with Michael Walzer, the U.S. Catholic bishops, and President Clinton. He concludes by showing how a casuistry of intervention is possible, developing a motivational rationale that draws on the Golden Rule. (shrink)