Abstract

In this article we focus on the jus in bello principle of necessity for guiding the use of autonomous weapons systems (AWS). We begin our analysis with an account of the principle of necessity as entailing the requirement of minimal force found in Just War Theory, before highlighting the absence of this principle in existing work on AWS. Overlooking this principle means discounting the obligations that combatants have towards one another in times of war. We argue that the requirement of minimal force is an important requirement for considering ethical uses of force. In particular, we distinguish between lethal and non-lethal purposes of use of force and introduce the prospect of non-lethal AWS before reviewing a number of challenges which AWS pose with respect to their non-lethal use. The challenges arise where AWS generate unpredictable outcomes impinging upon the situational awareness required of combatants to ensure that their actions meet the requirement of minimal force. We conclude with a call for further research on the ethical implications of non-lethal uses of AWS as a necessary contribution for assessing the moral permissibility of AWS.