Autonomous weapon systems (AWS) can select and engage targets without human intervention. They, therefore, act as both weapons and fighters in combat. The current legal rules governing these areas are written for humans to apply and abide by, with a subsequent responsibility regime for violations. Thus, as machines, AWS pose a challenge to these legal rules. This thesis asks if international law as it currently stands is sufficient to regulate AWS, or if new law is required?

This thesis presents a novel way of understanding the relationship between AWS and those who control them that is rooted in the lex lata. It demonstrates that AWS exist at the centre of ‘layers of control’ where the influence of political decision-makers, weapons reviewers, AWS developers, and AWS users can clearly be seen. Doing so views AWS as their legal agents, meaning that the legal regimes regulating weapons, targeting, and responsibility can be applied to the actions of AWS through these controlling entities.

Ultimately, this thesis concludes that, in most cases, current international law rules are sufficient to regulate the development, use, and responsibility for AWS. In coming to this conclusion through the ‘layers of control’ approach, it is argued that: the weapons law regime needs to be interpreted flexibly in order that the autonomous nature of AWS can be sufficiently considered; human beings must, for the foreseeable future, play a significant rule in the use of AWS; the entities controlling AWS must be seen as acting through these systems in order for responsibility to be sufficiently attributed to them.