Policing approaches that rely on repeated intrusion in the lives of citizens can be accompanied by public cynicism about the ability of legal institutions to ensure public safety. This study provides a quantitative assessment of the dynamics of phenomenon of overpolicing and underpolicing over time. It does so in the context of one of the largest cities in the Global South, with a focus on shifts in support for personal use of violence via diminished perceptions of legitimacy. Drawing upon a three-wave longitudinal survey representative of eight neighborhoods in São Paulo, Brazil, I demonstrate that perceptions of overpolicing and underpolicing (a) mutually reproduce each other over time, (b) vary significantly by neighborhood, (c) increase after aggressive police stops, (d) undermine police legitimacy, and (e) contribute to more favorable attitudes towards the acceptability of violence. This study provides further evidence on the costs of coercive policing, with significant implications for people’s recognition of the ruling power of legal authority.