As any survey of Islamic history will show, Muslims spoke about the rights and wrongs of employing armed force in a variety of ways. This presentation deals with one of these. The work of jurists in developing judgments pertaining to armed struggle provides one of the most extensive examples of the more general attempt by human communities to regulate the use of lethal force. In its form and substance, this aspect of Muslim tradition invites comparison with Christian notions about just war, as well as with a number of other religious and moral traditions. I begin with some general remarks regarding such traditions, then take up a number of questions related to the historic role of right authority in the Muslim law of war and peace. I then turn to contemporary jihadist rhetoric, suggesting that its focus on fighting as an individual duty points to a crisis of authority. I conclude with reflections on the responsibilities of scholars working in a troubled time.