Enforcement policies: Frequency of inspection is more important than the severity of punishment

External enforcement policies aimed to reduce violations differ on two key components: the probability of inspection and the severity of punishments. Different lines of research offer competing predictions regarding the relative importance of each component. In three incentive compatible studies, students and Prolific crowdsourcing participants (Ntotal=430) repeatedly faced temptations to commit violations under two enforcement policies. Controlling for expected value, the results indicated that a policy combining High probability of Inspection with Low Severity of fine (HILS) was more effective than a policy combining Low probability of Inspection with High Severity of fine (LIHS). Consistent with the prediction of Decisions from Experience research, this finding held even when the severity of the fine was stated in advance to boost deterrence. In addition, the advantage of HILS over LIHS was greater as participants’ baseline rate of violation (without enforcement) was higher, implying that HILS is more effective among frequent offenders.