Abstract
The European Union (EU) seeks to play a leading role in steering the private work of online content moderation, as demonstrated by numerous policy and legislative initiatives in the domain. Two initiatives, in particular, are shaping terrorist content moderation: the creation of a EU Internet Referral Unit and the adoption of a Regulation on preventing the online dissemination of terrorist content (TERREG). This article analyses these initiatives and their practical effects. In particular, it unpacks the legal and technological mechanisms at the core of EU regulation in the realm of online terrorist content moderation, and how they co-produce security decisions across public and private spheres. Based on interviews, fieldwork observations and document analysis, we show how processes of referral and removal, and processes of flagging and filtering are key to EU-directed content moderation. In conclusion, we reflect on content moderation as a novel form of European security integration.