Certainty, Severity, or Celerity? A Mixed‐Effects Analysis of Corruption and Deterrence in the European Union

Deterrence theory underpins numerous anti‐corruption interventions. Yet, empirical evidence on its application to corruption remains limited. Existing studies rely mainly on laboratory experiments and focus on certainty and severity of punishment, leaving the role of celerity unexplored. This study addresses these gaps by examining the three elements of deterrence—certainty, severity, and celerity—using data from 25 European Union countries across five time periods (2013–2024), while controlling for a range of social, political, and economic factors, most notably trust. Mixed‐effects analyses show that higher certainty of punishment is associated with lower corruption levels, but this relationship depends critically on celerity. When punishment is slow, certainty has no discernible association with corruption; when punishment is timely, this association is substantial. We found no evidence that laboratory‐based severity effects extend to real‐world corruption contexts. These findings indicate that effective deterrence strategies could prioritize measures that increase the perceived likelihood of punishment while simultaneously ensuring timely punishment. They also highlight the need for renewed theoretical and empirical attention to celerity as a conditional mechanism in deterrence processes.