In the past decade, Western European countries such as Germany, the Netherlands, the UK and France have seen a sharp increase in terrorism trials. Studying these trials can provide unique insights into which terrorist offences come before the court and what legal challenges arise from this relatively novel practice. To unpack the complexity of terrorism trials, we adopt an empirical approach to terrorism trials. Based on 3 years of extensive ethnography in Dutch courts, the paper makes two contributions to the socio-legal literature. Methodologically, our ethnography connects traditional empirical methods to artistic tools. As such, we further the current debates in socio-legal studies on courtroom ethnography. Empirically, we present critical insights on the interaction between pre-emptive speculative security measures and legal procedures in the prosecution of terrorist activities.