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Communicating Forensic Science

NCJ Number
Date Published
May 2015
13 pages
This project's broad goal was to expand the sparse knowledge about how jurors respond to forensic-identification expert testimony presented at trial.
Using a mock trial paradigm that consisted of fictitious criminal trials and a sample of laypersons as jurors, the project conducted three experiments, with each experiment examining one issue in jurors' responses to expert testimony on forensic analysis of evidence. One experiment examined jurors' responses to technology, the expert witness' experience, and scientific testing. The second experiment analyzed jurors' responses to exculpatory evidence presented by the defense and the subjective certainty of the expert witness. The third experiment addressed jurors' responses to scientific testing and error concessions by the expert witness. Overall, the findings suggest that jurors tend to over-value some attributes of forensic-science expert testimony and under-value other aspects. The most persistent finding is that jurors relied heavily on the "experience" of the testifying expert and the expert's asserted certainty in her/his conclusions. In contrast, jurors were apparently insensitive to variables indicative of the validity and accuracy of a forensic technique, including testimony about whether or not a technique has been empirically validated and whether evidence is presented to show that the technique is known to produce errors. This difference in the priorities of lay jurors and forensic scientists is troubling because there is no evidence that more experienced forensic scientists are any more competent or accurate than those who are less experienced. Implications of these findings are drawn for forensic evidence presentation at trial. The project's methodology is described in detail. 1 table

Date Published: May 1, 2015