The DNA revolution has revealed that, contrary to received wisdom, the conviction of an innocent defendant by the vaunted American criminal justice system is far from a freakish event. The National Registry of Exonerations now lists more than 2,200 cases of wrongful convictions. Of course, 2,200 cases is a minuscule number compared to the roughly 1.5 million felons in state and federal prisons at any given moment. The last quarter century has seen a vigorous debate about the error rate that leads to the conviction of innocent defendants. Estimates have ranged from 0.027% to 15%; most estimates are in the 0.5% to 2% range. This Article presents the first study to draw on an existing data set of actual claims of innocence to estimate the overall error rate in the criminal justice system. The data come from the North Carolina Innocence Inquiry Commission, a unique program that allows applications for exoneration from convicted felons. Conservative assumptions about the North Carolina data set produce a likely error rate of 0.125% to 0.5%. Though the estimates of the wrongful conviction rate are thus limited to North Carolina, there is no reason to think that the error rate is materially different in other states.
This Article is, in part, a response to Paul Cassell’s article, Overstating America’s Wrongful Conviction Rate? Reassessing the Conventional Wisdom About the Prevalence of Wrongful Convictions. Though the findings here as to the estimated error rate are higher than Professor Cassell’s, we do agree that previous estimates tend to be too high for reasons this Article will explore.