The principle of individual criminal responsibility for war crimes is one of the core principles of international humanitarian law (IHL). Punishing individuals for war crimes which are considered grave violations of the law of armed conflict is at the heart of the system of enforcement of IHL.

Starting first with whether - in light of their autonomous decision making powers in targeting - LAWS can be considered criminally responsible, there seems to be consensus among delegations of the GGE that the ‘legal responsibility will lie with the human’. Ultimately, it is the human involved in the deployment of LAWS who will be held criminally responsible for her/his actions. This is in line with one of the cardinal principles of criminal law that human action is a prerequisite for criminal responsibility. Indeed, under international criminal law war crimes can only be committed by individuals (and not by robots).

Mens Rea as One of the Conceptual Building Blocks of Individual Criminal Responsibility  

Despite definitional problems associated with the classification of autonomous weapon systems, these systems have or will have different degrees of decision making powers in selecting and engaging targets. Autonomy capabilities in existing and forthcoming weapon systems pose challenges to key requirements for ascribing criminal responsibility to individuals. One of them is the principle that criminal responsibility should be conditional on the presence of a mental element (mens rea). Mens rea refers to the requirement that an accused carries out a voluntary physical act with intent, purpose, knowledge, recklessness, negligence, or some other prescribed mental state.

Mens rea requirements vary depending on the crime and on the mode of responsibility. With regard to the latter, one possibility is to deploy, as a framework for the attribution of responsibility for war crimes, indirect modes of criminal responsibility, such as command responsibility (on which many have focused). Before that, however, it is crucial to look at the direct criminal responsibility for commission. This will ultimately also be a condition for the application of the doctrine of command responsibility whereby commanders are held criminally responsible for crimes committed by their human subordinates. With regard to the subjective element for war crimes, Article 30 of the Statute of the International Criminal Court (ICC) requires intent and knowledge as a general rule on mens rea. Moreover, specific war crimes relating to the methods of warfare require, in their definitions, additional subjective elements. Examples include the war crimes of killing (Article 8(2)(a)(i) ICC Statute) and causing great suffering (Article 8(2)(a)(iii) ICC Statute) requiring ‘willfulness’; and the war crime of attack on civilian population, civilian objects, protected buildings, and humanitarian missions (Articles 8(2)(b)(i), (ii), (iii), (ix), (xxiv), (e)(i), (ii), (iii), (iv) ICC Statute) which require ‘intentionality’. Similarly, all the grave breaches listed in Additional Protocol I to the Geneva Conventions (AP I) require that perpetration be ‘willful’; one example is launching an indiscriminate attack affecting the civilian population or civilian object (Article 85(3)(b) AP I)). 

A particularly thorny question is whether a commander/field officer who deploys the LAWS can be held responsible for the resulting war crimes when she/he did not intend war crimes to be committed. Given that LAWS may make targeting decisions autonomously, and given the very specific mens rea requirements for criminal responsibility for war crimes, how can a human being be held responsible for a war crime committed by LAWS? LAWS’ autonomy in selecting and engaging targets may prevent the ascription of individual criminal responsibility, begging the question of whether the use of LAWS in armed conflict requires rethinking the standards of attribution of criminal conduct.

The ‘Human Element in the Use of Lethal Force’ and Mens Rea 

Agreement among delegations on ‘the essential importance of human control, supervision, oversight or judgement in the use of lethal force’ allows us to predict that the ‘human element in the use of lethal force’ will certainly be a decisive factor in establishing restrictions to the development of autonomy. Focus, on the one hand, on the ‘human element’ and on concepts such as ‘meaningful human control’ and, on the other hand, on the tasks performed by LAWS, will frame the legal concerns for the years to come. The degree of human involvement and the corresponding level of autonomy of weapon systems are also crucial for the determination of criminal responsibility and beg fundamental questions of criminal law. How does ‘human control’ translate into mens rea? Will concepts and standards developed to limit LAWS’ lethal autonomy be able to ensure that the ‘human’ will be held criminally responsible?

In making policy choices on how autonomy is developed, questions of criminal responsibility for war crimes committed by LAWS must be considered. This is the objective of the LAWS and War Crimes Project, a four-year research project currently underway at the Graduate Institute of International and Development Studies.

Dr. Marta Bo on behalf of the LAWS and WAR Crimes Project

Post-doc at IHEID (LAWS and WAR Crimes Project) and Researcher at T.M.C. Asser Institute.