Measuring Self-Reported Wrongful Convictions among Prisoners

Abstract

Despite considerable interest in the subject of wrongful convictions, little is known about the incidence of wrongful convictions in the general prison population due in part to the difficult of measuring the frequency of errors in non-capital cases. We report the results of a survey of a population sample of state prisoners who were asked to anonymously report their involvement in the crimes for which they were most recently convicted. To assess the validity of verifiable responses, prisoner self-report data were compared to aggregate conviction and demographic information derived from administrative records. To assess the validity of unverifiable responses, we developed a non-parametric test to estimate the probability of false innocence claims. Based on this survey and test, we estimate that wrongful convictions occur in 6% of criminal convictions leading to imprisonment in an intake population of state prisoners. This estimate masks a considerable degree of conviction-specific variability ranging from a low of 2% in DUI convictions to a high of 40% in rape convictions. We consider these estimates to be upper bounds on the actual incidence of wrongful convictions within each of these populations. Implications for future research on wrongful convictions are discussed.

Keywords: Wrongful Convictions; Self-Report, Prisoner

JEL Classification: K14, K40