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Enhancing Fairness in DNA Jury Trials

NCJ Number
Jane Goodman-Delahunty; Lindsay Hewson
Date Published
March 2010
6 pages
This study identified factors that can be used to improve jury understanding and use of DNA evidence.
Data show that the use of DNA evidence in Australian courts has increased considerably since 1989. The data also show that juries were 23 times more likely to vote guilty in homicide cases and 33 times more likely to vote guilty in sexual assault cases when DNA evidence was admitted at court. Post-trial interviews of jurors indicate, however, that jurors often have difficulty understanding the DNA evidence presented at trial, yet still continue to convict the defendant. This study was conducted to identity factors that could be used to improve jury understanding of DNA evidence. The study looked at the following: whether expert evidence enhanced juror DNA knowledge; whether visual information enhanced understanding compared to information conveyed verbally; whether strong DNA evidence increased conviction rates compared to inconclusive DNA evidence; and whether greater understanding of DNA evidence reduced convictions. This paper examines the expert tutorial that was developed by legal counsel, and medical and forensic scientists. The tutorial was administered to a representative sample of 470 Australians. The study found that for those who received the expert tutorial, their understanding of DNA evidence significantly increased compared to those who did not receive the tutorial. The use of multimedia in presenting the DNA evidence had no significant effect on jurors' understanding and use of the evidence. In addition, the study found that enhanced DNA knowledge by jurors increased their skepticism about DNA experts and reduced their convictions of defendants. Policy issues for decisionmakers are discussed. Tables, figure, and references