Exoneration Statistics and Databases
Much of our work has focused on “DNA exonerations” – these represent only a small portion, about 15%, of all exonerations. DNA exonerations are cases in which DNA evidence is instrumental in proving innocence, and so these tend to be crimes with blood or other bodily fluids, such as sexual assault or homicide
A “DNA Exoneration” is a case in which post-conviction DNA testing results were central to establishing the innocence of the wrongfully convicted individual, i.e., the DNA testing results were dispositive of actual innocence and central to vacating the conviction and/or dismissing the indictment. The indictment must have been dismissed or the defendant pardoned on the grounds of innocence or acquitted at a retrial.
As of September 2019, we have documented 365 DNA exoneration cases in the United States, including 20 death penalty cases. Although the individuals involved in these cases were innocent of the crime, approximately 25% had confessed or admitted guilt and 11% had plead guilty. The exonerees spent an average of 14 years in prison, with 10% serving 25 or more years. Additional information about the DNA exoneration cases is available here and a summary based on the first 325 cases has been published in the Albany Law Review.
The Innocence Project’s Science and Research department contributes to the National Registry of Exonerations (NRE) database and to a database developed in conjunction with the book, Convicting the Innocent, an analysis of the first 250 DNA exonerations published in 2011 by Brandon Garrett. The NRE database includes all exonerations in the United States, including cases in which DNA played no or a limited role in the exoneration. In 2019, the NRE database contained more than 2,400 cases. Their website is well-suited for sorting and sub-setting cases and provides a tabular display of cases showing variables relating to crime details and factors contributing to the wrongful conviction. Datasets are available upon request. The Convicting the Innocent database is limited to DNA exonerations, using the same definition that we use. It has search and graphical capabilities and includes some trial transcripts and other documents and citations to judicial decisions. This database is updated annually; in 2019, this database included 350 cases.
The Innocence Project’s Science and Research department conducts comprehensive reviews of research relating to critical issues and questions that underlie efforts to prevent wrongful convictions. One area of research has been the influence of cognitive bias at various stages in the investigation and prosecution of a crime. An overview of this work, “Criminal Investigations, Cognitive Bias, and Wrongful Conviction,” was presented at the 2017 annual meeting of the American Society of Criminology, and a summary of cognitive bias-forensic science research that included 29 studies in 14 different disciplines, “Cognitive Bias Research in Forensic Science: A Systematic Review,” was published in 2019 in Forensic Science International.
Eyewitness Identification – The 2014 National Academy of Sciences report Identifying the Culprit: Assessing Eyewitness Identification, examines the scientific understanding of visual perception and memory and the implications of this understanding for developing best practices for the investigation of crimes and presentation of eyewitness evidence. Additional information and new recommendations can be found in an updated review by Gary Wells et al., available in draft form.
False Confessions – One of the lessons learned from examination of more than 350 DNA exonerations is that, although it may seem unimaginable, innocent people confess to crimes they did not commit. Insights and recommendations have been made based on the work of social scientists’ and legal scholars’ studies of ways in which human psychology and specific interrogation techniques influence risk of false confession, but this is an area needing additional research.
Forensic Science – There has been considerable progress in some areas relating to forensic science since the 2009 National Academy of Sciences report, Strengthening Forensic Science in the United States: A Path Forward. The Center for Statistics and Applications in Forensic Evidence, initially funded in 2015, is now a multi-institutional, interdisciplinary collaboration with more than 60 researchers in statistics, computer science, machine learning, engineering, and law. To highlight the contributions of statisticians working in this area, the Innocence Project helped coordinate a special issue of Significance, a journal of the Royal Statistical Society and the American Statistical Association, including articles discussing the need for objective measurements, reliability and validity, and the .
Guilty Pleas – The Innocence Project contributed two papers to the April/June 2019 issue of Federal Sentencing Reporter focusing on “the trial penalty:” a first-hand look at the experience of someone who faced the pressures and consequences of an offer of a plea deal for a crime he did not commit , and an analysis based on the 362 DNA exonerations examining demographic, crime-related, and sentencing factors associated with the decision of people to plead guilty to a crime they did not commit.
Another resource for information on wrongful convictions is the Innocence Research website, a compilation of research on wrongful conviction, popular media resources, upcoming symposia and meetings, and other useful resources for teachers, policy makers, researchers, and the general public.
To encourage new research to address important knowledge gaps relating to wrongful convictions, we periodically survey staff to solicit their input regarding unanswered questions and issues that affect their work. A summary of this work was presented at the American Psychology-Law Society annual conference in 2018.
Innocence Project Publications
West E, Meterko V. Innocence Project: DNA Exonerations, 1989-2014: Review of Data and Findings from the First 25 Years. Albany Law Rev. 2016;79:717-794.
Meterko V. Strengths and Limitations of Forensic Science: What DNA Exonerations Have Taught Us and Where to Go From Here. West Virginia Law Rev. 2016;119:639-649.
Cooper GS, Meterko V. Cognitive bias research in forensic science: A systematic review. Forensic Sci Int. 2019;219:35-46.
Cooper GS, Meterko V, Gadtaula P. Innocents Who Plead Guilty: An Analysis of Patterns in DNA Exoneration Cases. Federal Sentencing Reporter. 2019;31:234-238. DOI: 10.1525/fsr.2019.31.4-5.234
Ochoa C, Salazar C. How the Threat of the Trial Penalty Coerces the Innocent to Plead Guilty: A First-Hand Account of an Exoneree. Federal Sentencing Reporter. 2019;31:299-302. DOI: 10.1525/fsr.2019.31.4-5.299
Mejia R, Cuellar M, Delger D, Eddy B. What does a match mean? A framework for understanding forensic comparisons. Significance. 2019;16: 25-28.