University of Notre Dame
Kroc Institutde for International Peace Studies

Ethicists and international legal experts speaking at the Kroc Institute conference (March 19-21) raised concerns about the implications of drone warfare. Martin Cook (U.S. Naval War College) noted that drone weapons reduce the risk to U.S. forces and result in fewer civilian casualties, but they may increase the temptation to use force. They may be “tactically smart but strategically dumb,” he said.

The justifications for drone warfare offered by Obama administration officials invoke the jus ad bellum and jus in bello criteria of just war doctrine, presenters said, but they fail to mention the core principle at the heart of this doctrine:  the presumption against the use of force. Just war principles of discrimination and last resort are often cited in rhetoric but are frequently violated in practice.

Under jus ad bellum criteria, Jennifer Welsh (Oxford University) argued, military force can be used only under very specific and necessary circumstances:  if there is a grave threat of genocidal attack or military aggression, if that threat is actual rather than merely potential, if there is clear evidence that the intended target is liable for the observed threat, and if no possibility exists to capture those responsible.

Similar strict criteria exist for the principle of self-defense, which is valid only in response to an existing attack from an armed group and only against combatants who are engaged in active hostilities. It cannot be applied to an attack that took place 12 years ago or to one that may occur at some indeterminate date in the future. By discounting the possibility of negotiation and using force outside an acknowledged war zone, drone strikes re-conceptualize and weaken the principle of last resort.

Susan Brooks Thistlethwaite (Chicago Theological Seminary) expressed concern that by making military operations less risky and more removed from society, drones increase the temptation to use force and diminish political and moral accountability. Any development that makes war appear to be easier and cheaper is cause for concern, she said. She called for an end to the use of illegal drone strikes as a moral imperative.

The legal justifications offered for drone warfare beyond an armed conflict zone are deficient under international law. Karen Greenberg (Fordham University) linked current U.S. legal arguments for such strikes to the justifications offered for indefinite detention, noting that the administration has apparently chosen to kill rather than detain terrorism suspects. Mary Ellen O’Connell (University of Notre Dame Law School) noted that the UN Charter prohibits the use of armed force without UN Security Council authorization, unless in self-defense to actual armed attack.


The recently revealed 16-page white paper from the Obama administration distorts just war principles, panelists noted. The authors of the white paper twist words in an attempt to separate the concept of imminence from immediacy: “The condition that an operational leader presents an ‘imminent’ threat against the United States does not require the United States to have clear evidence that a specific attack on the United States will take place in the immediate future.”

The white paper also cites the precedent of the Nixon administration’s invasion of Cambodia to make its case for bombing strikes in non-belligerent countries. The document refers to a May 1970 statement by John R. Stevenson, State Department Legal Advisor at the time, claiming that the United States had previously refrained from attacking Cambodia. In fact, President Nixon began a large-scale secret bombing campaign in Cambodia more than a year before and systematically covered up the fact. Stevenson may not have known this when he made his statement, but officials of the Obama administration should have known, since the relevant documents were released years ago. As Mary Dudziak (Emory University) stated at the conference and wrote in her recent New York Times op ed, “The Cambodia bombing can’t be used to justify today’s drone attacks.”

Lawmakers in Congress have proposed the creation of a judicial court to oversee the selection of targets for drone strikes. Panelists at the conference uniformly dismissed this idea as neither desirable nor feasible. The creation of what some have called an ‘assassination court’ would confer legitimacy on the policy of targeted killing and impede efforts to place the program under international law.

As Pardiss Kebriaei (Center for Constitutional Rights) observed, if the government claims to respect the principle that strikes are only permissible in the face of an imminent threat, the requirement for a prior time-consuming judicial approval process makes no sense.


The U.S. policy of drone warfare is an integral component of the so-called global war on terrorism. The main concern with drones is not the technology itself but how they are used. Unmanned aerial vehicles offer potential benefits for law enforcement, environmental monitoring, human rights protection, and nonproliferation inspection, but their use for targeted killing is questionable ethically, legally, and strategically.

Many have called for rules and a regulatory framework for drone usage. The Obama administration reportedly has worked on developing such a framework. As legal experts at the conference emphasized, however, rules for regulating drone warfare already exist. They are embodied in the laws of armed conflict, International Human Rights Law and International Humanitarian Law. Applying the existing standards of international law offers the best approach for regulating the use of drone weapons.

The Authorization to Use Military Force, adopted by Congress in September 2001 and renewed each year in Congressional defense authorization acts, provides blanket authority for the use of “all necessary and appropriate force” against those responsible for the 9/11 attacks and affiliated forces. This resolution is the charter for the war on terror and has been used by the government to justify widespread military operations without geographic or temporal limits. It has been interpreted as a license to engage in unrestricted drone warfare.

As long as this authority remains in force, it will be difficult to place legal limits on U.S. drone policy. Several speakers at the conference suggested the time has come to withdraw this authorization and end the so-called global war on terror.

—David Cortright