For more than a decade, states have met at the UN in Geneva to discuss the governance of autonomous weapon systems (AWS). One pandemic, several real-world cases of artificial intelligence (AI) being used in targeting decisions, and numerous meetings later, there is a growing consensus among states that the challenges posed by AWS should be addressed through both prohibitions and restrictions, a so-called ‘two-tier’ approach. But while there is progress on the basic structure (i.e. two tiers), the actual content of these tiers is debated.

To help states elaborate on possible elements of a two-tiered approach to the governance of AWS, Laura Bruun from the Stockholm International Peace Research Institute (SIPRI) points to three lessons from past arms control negotiations that can be applied to the AWS debate: First, a prohibition does not need to be grounded in a clearly defined class of weapons, second, restrictions can be used to clarify what international humanitarian law (IHL) requires in the specific context of AWS, and third, if there is will (and a need), two-tiered instruments can be grounded in concerns beyond IHL.