Post-Conviction DNA Testing and Wrongful Conviction

• NCJ Number: 238816
• Author(s): John Roman Ph.D.; Kelly Walsh Ph.D.; Pamela Lachman; Jennifer Yahner
• Date Published: June 2012
• Length: 69 pages
• Grant Number(s): 2008F-08165
• Agencies: NIJ-Sponsored
• Publication Type: Report (Study/Research)

Annotation

This retrospective study, using data from post-conviction DNA analyses, attempts to estimate the rate at which defendants are wrongly convicted on charges of sexual assault and/or homicide, and identify case attributes (i.e. predictors) associated with those wrongful convictions.

Abstract

Only in the past decade has the use of DNA testing to include or eliminate suspects, and exonerate those convicted, in serious crimes become relatively common. Thus, it is possible that some convicted in serious crimes (sexual assault and homicide) would have been eliminated by forensic analysis more discriminating than what was available at the time. This study examined a cohort of serious crime convictions between 1973 and 1987 from Virginia to answer a critical policy question: "What proportion of convicted offenders in serious crimes with retained forensic evidence could be exonerated if that evidence were DNA tested?" The authors first determined whether the results of DNA testing would support exoneration of a convicted defendant, inculpate the defendant, or be insufficient to change the outcome of the case, noting that it is critical to keep in mind that the data collection was largely limited to forensic files, and because of this, it must be assumed that the forensic evidence is sufficiently probative to make such a determination for each conviction. It is possible that other non-forensic facts of the case that are not available may lead to a different conclusion. Additionally, the authors used these data to identify associations between case characteristics and the likelihood that DNA testing would produce determinate results and support exoneration of a convicted defendant. These findings can be used by States to prioritize closed cases for post-conviction DNA analysis. If those attributes include factors that exist today policy recommendations can be made to avoid new wrongful convictions.