We study the implications of police discretion for public safety. Relying on variation across highway patrol officers in their propensity to issue harsh fines, we show that higher fines reduce future traffic offending. Motorists most likely to face harsh sanctions are least deterred by fines, inconsistent with an allocation of sanctions that maximizes public safety, and most likely to reoffend, suggesting an alternative model of officer behavior. Counterfactual punishment allocations can reduce the aggregate reoffending rate by as much as seven percent, highlighting efficiency costs associated with current officer practices, but require that the lowest risk drivers face harsh punishments.