E) Challenges Posed by Certain New Technologies of Warfare to Legal Reviews of New Weapons
As noted above, the development and use of new technologies of warfare, such as autonomous weapon systems or military cyber capabilities, do not occur in a legal vacuum. As with all weapon systems, they must be capable of use in compliance with IHL, particularly its rules on the conduct of hostilities. The responsibility for ensuring this rests with every State that is developing, acquiring and using these new technologies of warfare. In this respect, legal reviews are as critical now as they were when Article 36 of Additional Protocol I was conceived during the Cold War arms race. To assist States in implementing this obligation, in 2006, the ICRC published A Guide to the Legal Review of New Weapons, Means and Methods of Warfare: Measures to Implement Article 36 of Additional Protocol I of 1977. What follows is drawn from that Guide and addresses new questions regarding the challenges to legal reviews posed by new technologies of warfare.
Every State party to Additional Protocol I is obliged to determine whether the employment of a new weapon, means or method of warfare that it studies, develops, acquires or adopts would, in some or all circumstances, be prohibited by international law.40 In the ICRC’s view, the requirement to carry out legal review of new weapons also flows from the obligation to ensure respect for IHL under Article 1 common to the Geneva Conventions.41 Besides these legal requirements, all States also have an interest in assessing the lawfulness of new weapons. Legal reviews are a critical measure to help ensure that a State’s armed forces can conduct hostilities in accordance with that State’s international obligations. They also help prevent the costly consequences of approving and procuring a weapon the use of which is likely to be restricted or prohibited.
Weapon systems of all types should be subjected to legal review, including physical systems (hardware) and digital systems (software). This extends to military cyber capabilities intended for use or expected to be used in the conduct of hostilities. It also includes software components that form part of the weapon system (the “means” of warfare) or the way in which the system will be used (the “method” of warfare), such as software that controls a physical system or supports decision-making processes for use of that weapon system. Since a weapon cannot be assessed in isolation from the way in which it will be used, the normal or expected use of the weapon must be considered in the legal review.
Weapons that include a software component that permits the critical functions of selection and attack of targets (the defining characteristics of autonomous weapon systems) to be triggered by the weapon system’s environment, rather than by a commander, make it challenging to assess whether the weapon can be used in compliance with IHL rules. A reviewer will need to be satisfied that the proposed weapon’s design and method of use will not prevent a commander from exercising the judgement required by IHL. If the reviewer is not satisfied of this, they must not allow the weapon to be used; alternatively, they may need to impose limitations on the weapon’s use to ensure the commander’s ability to comply with IHL.
Foreseeing the effects of weapon systems through testing may become increasingly difficult, as weapon systems become more complex or are given more freedom of action in their tasks, and therefore become less predictable, such as weapon systems that incorporate machine learning. Unpredictability in the functioning of the system, and the interaction of the system with a dynamic environment, cannot be simulated in advance of use. This challenge will be compounded, in some cases, by the inability of the commander to understand how a weapon system using artificial intelligence – particularly machine learning – reaches its output from a given input, which makes it difficult (if not impossible) to foresee the consequences of its use.
For legal reviews to be effective, States that develop or acquire new weapon technologies need to navigate these complexities. Therefore, legal reviews of weapons, means and methods of warfare, relying on these new technologies may need to be conducted at an earlier stage of weapon development, and at shorter intervals, than for more traditional technologies, and may need to be repeated during development. The unique characteristics of new technologies and the related processes of legal review require new standards of testing and validation. States should also share information about their legal-review mechanisms and, to the extent feasible, about the substantive results of their legal reviews, especially where a weapon’s compatibility with IHL may be in question – so that other States will not encounter the same problems and can benefit from reviewing States’ conclusions on whether the use of the weapon in question is prohibited or restricted by IHL. When States exchange information about conducting legal reviews of new technologies, it can help build expertise and identify good practices, and also assist States that wish to establish or strengthen their own mechanisms.
40 Sweden and the United States, for example, first established mechanisms for legal review in 1974, three years before the adoption of Additional Protocol I.
41 This is also the view of some States. See Australia, “The Australian Article 36 review process”, working paper submitted to the Group of Government Experts of the High Contracting Parties to the Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons Which May be Deemed to be Excessively Injurious or to Have Indiscriminate Effects (CCW), 2018, para. 3; […]; The Netherlands and Switzerland, “Weapons review mechanisms”, working paper submitted to the CCW, 2017, para. 17.
ICRC, International Humanitarian Law and the Challenges of Contemporary Armed Conflicts: Recommitting to Protection in Armed Conflict on the 70th Anniversary of the Geneva Conventions (October 2019) 34–35
