Cassell publishes new research on prevalence of wrongful convictions, concluding rate is lower than estimates

New research published by University of Utah S.J. Quinney College of Law Professor Paul Cassell  in the Arizona Law Review explores the prevalence of wrongful convictions in America’s criminal justice system, concluding that it is much lower than previously estimated.

Cassell’s first article – Overstating America’s Wrongful Conviction Rate? Reassessing the Conventional Wisdom About the Prevalence of Wrongful Convictions – discusses a growing body of academic literature about the problem of wrongful convictions — i.e., convictions of factually innocent defendants for crimes they did not commit. How often do such miscarriages of justice actually occur? Justice Scalia cited a figure of 0.027 percent as a possible error rate. But the conventional view in the literature is that, for violent crimes, the error rate is much higher — at least 1 percent, and perhaps as high as 4 percent or even more.

Paul G. Cassell, a Ronald N. Boyce Presidential Professor of Criminal Law at the University of Utah’s S.J. Quinney College of Law. Photo by Benjamin Hager.

Cassell’s article critiques that conventional wisdom. Based on a careful review of the available empirical literature, Cassell assembles the component parts of a wrongful conviction rate calculation by looking at error rates at trial, the ratio of wrongful convictions obtained through trials versus plea bargains, and the percentage of cases resolved through pleas. Combining empirically based estimates for each of these three factors, a reasonable (and possibly overstated) calculation of the wrongful conviction rate appears, tentatively, to be somewhere in the range of 0.016 percent–0.062 percent — a range that comfortably embraces Justice Scalia’s often-criticized figure, according to Cassell.

Cassell noted that if his tentative error-rate range is correct, then previous scholarship has significantly overstated the risk of wrongful conviction. Moreover, Cassell compared the lifetime risk of being wrongfully convicted to the risk of being a victim of a violent crime. The relative risk ratio appears to be about 30,000 to 1.

“This decidedly skewed ratio suggests that reform measures for protecting the innocent may need to be cautiously assessed to ensure that they do not interfere with the important goal of prosecuting the guilty,” said Cassell.

Cassell’s article was published as part symposium, in which professor George Thomas of Rutgers wrote a partial response.  Thomas used data 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 percent to 0.5 percent. Thomas’ article agrees with Cassell that previous estimates of the wrongful conviction tend to be generally too high.

A reply article by Cassell – Jurisdiction-Specific Wrongful conviction Rate Estimates: The North Carolina and Utah Examples – explores Thomas’ North Carolina estimate and offers a new estimate from Utah.   Cassell concludes that Thomas’ estimate from North Carolina is somewhat too high. Cassell then looks at Utah, concluding that a jurisdiction-specific error rate range for the state might be around 0.017 percent-0.066 percent.

 “Properly calculated, the wrongful conviction rates for North Carolina and Utah support my initial estimate of a wrongful conviction rate in this country much lower than the rates commonly suggested in other wrongful conviction literature,” Cassell concluded. “Both (Cassell) and Thomas underscore the important point of convergence between all their estimates: both are much lower than the conventional wisdom on the subject suggests.”

Cassell teaches in the areas of criminal procedure, criminal law, and crime victims’ rights at the S.J. Quinney College of Law.  The previously served as a federal judge.