T. A. Cavanaugh defends double-effect reasoning (DER), also known as the principle of double effect. DER plays a role in anti-consequentialist ethics (such as deontology), in hard cases in which one cannot realize a good without also causing a foreseen, but not intended, bad effect (for example, killing non-combatants when bombing a military target). This study is the first book-length account of the history and issues surrounding this controversial approach to hard cases. It will be indispensable in theoretical ethics, applied ethics (especially medical and military), and moral theology. It will also interest legal and public policy scholars.