That is the title of this 2012 book edited by Claire Finkelstein, Jens David Ohlin, and Andrew Altman. This tome (pictured below) contains 18 essays by a wide variety of scholars. Jeremy Waldron, for example, explores the morality associated with targeted killings and argues against the use of this tactic, while Fernando Teson, by contrast, argues that targeted killings are justified against terrorists because they use tactics specifically designed to kill civilians. If you don’t feel like reading an entire book, here is a good primer on the legality of the U.S. military’s existing targeted killing program (via Lawfare). For my part, although I do not address the tactic of targeted killing, here is my 2012 contribution on the “logic of terrorism.”