Police departments are increasingly relying on surveillance technologies to tackle public security issues in smart cities. Automated facial recognition is deployed in public spaces for real-time identification of suspects and warranted individuals. In some cases, law enforcement is going even further by exploiting also emotion recognition technologies. In preventive operations indeed, emotion facial recognition (EFR) is being used to infer individuals' inner affective states from traits like facial muscle movements. In this way, law enforcement aims to obtain insightful hints on unknown persons acting suspiciously in public or strategic venues (e.g. train stations, airports). While the employment of such tools still seems to be relegated to dystopian scenarios, it is already a reality in some parts of the world. Hence, there emerges a need to explore their compatibility with the European human rights framework. The Chapter undertakes this task and examines whether and how EFR can be considered compliant with the rights to privacy and data protection, the freedom of thought and the presumption of innocence.Isadora Neroni Rezende is a PhD Candidate in Law, Science and Technology -Rights of the Internet of Everything.