The Societal Cost of the Exclusionary Rule: An Empirical Assessment

A key criticism that has emerged in the debate over the search and seizure exclusionary rule is that it exacts heavy societal costs in the form of lost prosecutions and that such costs outweigh any demonstrated social benefits. This article examines the costs of three exclusionary rules using data collected for 7,500 cases in a nine-county study of criminal courts in three states. It emphasizes motions to suppress physical evidence but for comparative purposes also includes motions to suppress confessions and identifications. The results show that the various exclusionary rules exact only marginal social costs. Motions to suppress physical evidence are filed in fewer than 5% of the cases, largely drug and weapons cases, while serious motions to suppress identifications and confessions are filed in 2% and 4% of the cases. The success rate of motions to suppress is equally marginal. Successful motions to suppress physical evidence occur in only 0.69% of the cases, while successful motions to suppress identifications or confessions occur much less often. Moreover, not all who successfully suppressed evidence escaped conviction, especially when only an identification or a confession was suppressed. In all, only 46 cases—less than 0.6% of the cases studied—were lost because of the three exclusionary rules combined, most of them involving offenses that would have incurred less than six months' imprisonment or first offenders. Finally, the impact of unsuccessful motions on subsequent plea bargaining was found to be marginal; only unsuccessful motions to exclude confessions resulted in any real sentencing concessions.