The fifteen new essays collected in this volume address questions concerning the ethics of self-defense, most centrally when and to what extent the use of defensive force, especially lethal force, can be justified. Scholarly interest in this topic reflects public concern stemming from controversial cases of the use of force by police, and military force exercised in the name of defending against transnational terrorism. The contributors pay special attention to determining when a threat is liable to defensive harm, though doubts about this emphasis are also raised. The legitimacy of so-called stand your ground policies and laws is also addressed. This volume will be of great interest to readers in moral, political, and legal philosophy.