The article explores the evolving positions and negotiation strategies of the EU and its member states regarding lethal autonomous weapon systems (LAWS). Specifically, it traces the proceedings around the UN disarmament forum Convention on Certain Conventional Weapons (CCW) from 2013 to 2020. Embedded in the norm contestation literature, the empirical section draws upon semi-structured interviews as well as document analysis. We find that, despite the absence of a CFSP position on the matter, the EU and key member states have been instrumental in shaping the discussions. However, the role of the EU is constrained due to double contestation. First, at the level of member states contestation persists on what is the appropriate regulatory framework (hard or soft law). Second, contestation is also exerted towards the EU by some member states who contest the EEAS's involvement. Some are conscious that presenting an "EU position" might constrain their ability to build global coalitions. Others do not want the EU to interfere with their national sovereignty on such a critical security issue. While these two elements work against a common EU position, we also observe a window of opportunity for the EU. Notably, the EU can strengthen the CCW by funding the forum structures and secretariat, which could become an important body in the implementation of foreseeable agreements.