"Out of the loop": autonomous weapon systems and the law of armed conflict

The introduction of autonomous weapon systems into the “battlespace” will profoundly influence the nature of future warfare. This reality has begun to draw the attention of the international legal community, with increasing calls for an outright ban on the use of autonomous weapons systems in armed conflict. This Article is intended to help infuse granularity and precision into the legal debates surrounding such weapon systems and their future uses. It suggests that whereas some conceivable autonomous weapon systems might be prohibited as a matter of law, the use of others will be unlawful only when employed in a manner that runs contrary to the law of armed conflict’s prescriptive norms governing the “conduct of hostilities.” This Article concludes that an outright ban of autonomous weapon systems is insupportable as a matter of law, policy, and operational good sense. Indeed, proponents of a ban underestimate the extent to which the law of armed conflict, including its customary law aspect, will control autonomous weapon system operations. Some autonomous weapon systems that might be developed would already be unlawful per se under existing customary law, irrespective of any treaty ban. The use of certain others would be severely limited by that law. Furthermore, an outright ban is premature since no such weapons have even left the drawing board. Critics typically either fail to take account of likely developments in autonomous weapon systems technology or base their analysis on unfounded assumptions about the nature of the systems. From a national security perspective, passing on the opportunity to develop these systems before they are fully understood would be irresponsible. Perhaps even more troubling is the prospect that banning autonomous weapon systems altogether based on speculation as to their future form could forfeit their potential use in a manner that would minimize harm to civilians and civilian objects when compared to non-autonomous weapon systems