In light of the estimate that more than 40 countries now possess drone technology, the issue of targeted killing is not likely to fade in importance. In fact, targeted killing does not even require the use of advanced technology -- Israeli agents allegedly suffocated a Hamas leader with a pillow, and Russian security forces are alleged to have used a poison letter to kill a Chechen rebel commander. And the U.S. commando raid that killed Osama bin Laden was, arguably, the most important targeted killing in the history of the United States.

Some of the questions the essays in this volume address are as follows: What is targeted killing in a military context and what is the theory under which such killings may be permissible? If targeted killing is justified as a military necessity, are there any deontological constraints on the range of permissive topics? Should targets be restricted to traditional belligerents only? Or do civilians transform themselves into legitimate targets by threatening the interests or security of the United States? How does this transformation occur? Does the law of war confine lawful attacks to conventional battlefields or has the specter of terrorism transformed the entire world into a global battlefield?

A second section examines the tradeoffs implicit in consequentialist arguments supporting targeted killings. Is necessity a proper framework for justifying targeted killings, and if so are there any limits to the use of tradeoffs to justify the utilitarian foundation implicit in necessity claims? Do law and morality break down at the margins when military and civilian leaders are forced to take drastic action to stop deadly terrorist attacks? Or, in contrast, are targeted killings against marked individuals the logical extension of a legal regime that promotes surgical strikes and prohibits the kind of carpet bombing most likely to cause collateral damage?

A third set of issues deals more specifically with the proper scope of self-defense in the targeted killings debate. Does national self-defense under the U.N. Charter follow parallel principles to personal self-defense in domestic criminal law systems? Is self-defense available as a justification under international law when the threat of terrorism comes from a non-state actor? Finally, what is the status of targeted killing according to traditional just war theory? More specifically, does the doctrine of self-defense allow for preemptive action? Are targeted killings only justified as defensive force when detention is impossible? Must the threat from the target be imminent before self-defense is allowed, and how does this requirement relate to the traditional imminence requirements in jus ad bellum and domestic criminal law?

A fourth category tackles the independence of jus in bello from jus ad bellum. Is it relevant to the legal analysis that the United States is involved in a justified campaign against a non-state group devoted to terrorism? Can a "neutral" law regarding targeted killings apply both to the United States and to our enemies? In particular, the moral equality of combatants represents a unique, bedrock principle of the law of war that does not exist in domestic criminal war, where the right to kill is conferred only on victims of aggression, not the aggressors themselves. When exactly does a situation transform from one governed by criminal law to one governed by the radically different laws of war?

Finally, the volume concludes with a consideration of the asymmetry inherent in targeted killings. Drone operators working remotely in Virginia (or elsewhere) launch lethal attacks against the enemy, but do not subject themselves to the reciprocal risk of killing. This asymmetry reduces the disincentives usually associated with launching a military attack, which traditionally involved great risks to one's military personnel. The use of private military contractors in this context also reduces this risk and further exacerbates the asymmetry of modern warfare.

These questions arise at the intersection of moral, political, and legal theory, just war theory, national security law, public international law, international humanitarian law, as well as criminal law theory. Thus the volume is truly an interdisciplinary effort to marry the perspective of practitioners and applied legal scholars on the practice of targeted killing to that of philosophers seeming moral and political justifications for this particular aspect of war.