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Wrongful Convictions and DNA Exonerations: Understanding the Role of Forensic Science

NCJ Number
Date Published
September 2017
10 pages
This study examined publicly available data on erroneous convictions, with a focus on those cases that cite forensic science evidence as a contributor to the wrongful conviction, so as to identify what can be learned from these cases to improve the reliability of forensic evidence, the interpretation of results, and subsequent erroneous testimony.
The author cautions that the determination of whether forensic science testimony was a contributing factor in an erroneous conviction involves a degree of subjectivity. This is because the majority of erroneous convictions involve complex investigations, multiple contributing factors, complicated juror decisions, and mistakes due to policies and practices that have since changed. Also, examiners of these cases do not have all of the details or full transcripts from the evidence and testimony presented at trial. In addition, forensic methods most often associated with wrongful convictions through the 1990s have become more exacting with the evolution of DNA analysis. Five lessons are drawn from this study. First, forensic laboratories and scientists must make every effort to prevent forensic misconduct. Second, forensic scientists must avoid ambiguous terminology in their reports and testimony. Third, forensic scientists must convey impartial and objective conclusions based on accurate and reliable techniques. Fourth, when errors do occur, it is critical to focus on the underlying problems that contributed to the error and prevent its recurrence. Fifth, forensic testimony must not go beyond the limits of established scientific knowledge.

Date Published: September 1, 2017