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Tuesday, March 10, 2020

Considering forensic science: individual differences, opposing expert testimony and juror decision making

In criminal and civil trials around the world, both sides will often retain experts in various forensic science fields to analyze evidence and present their findings to the jury. In a fair process, and employing science, it's hoped that two similarly trained and equipped will arrive at the same place in terms of conclusions. But, this is often not the case.

When experts disagree, judges (acting as gatekeepers) will often allow both sides to present their witnesses and their evidence, relying upon juries (as finders of facts) to decide on the truth of the matter. One is left to wonder, how reliable are juries in accurately engaging in this essential task?

A fascinating study was published in 2018 that seeks to address this issue. In Considering forensic science: individual differences, opposing expert testimony and juror decision making (link), the authors seek to answer this question.

Abstract: "Two experimental studies examined the effect of opposing expert testimony on perceptions of the reliability of unvalidated forensic evidence (anthropometric facial comparison). In the first study argument skill and epistemological sophistication were included as measures of individual differences, whereas study two included scores on the Forensic Evidence Evaluation Bias Scale. In both studies participants were assigned to groups who heard: (1) no expert testimony, (2) prosecution expert testimony, or (3) prosecution and opposing expert testimony. Opposing expert testimony affected verdict choice, but this effect was mediated by perceptions of reliability of the initial forensic expert's method. There was no evidence for an effect on verdict or reliability ratings by argument skill or epistemology. In the second experiment, the same mediation effect was found, however scores on one subscale from the FEEBS and age also affected both verdict and methodological reliability. It was concluded that opposing expert testimony may inform jurors, but perceptions of the reliability of forensic evidence affect verdict, and age and bias towards forensic science influence perceptions of forensic evidence. Future research should investigate individual differences that may affect perception or bias towards forensic sciences under varying conditions of scientific reliability."

A fascinating and informative read.

Enjoy your day, my friends.

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