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Publication Date



Jury reforms, MtDNA, Scientific evidence, Expert testimony, Jury trial innovations, Mitochondrial DNA, Juror understanding of DNA evidence


Evidence | Science and Technology Law


A single spot of blood on a pink windowsill will tell investigators who broke a windowpane, turned a lock, and kidnapped 2-year-old Molly Evans from her bedroom in the middle of the night. An expert witness will testify that the DNA profile of the blood evidence recovered from the windowsill was entered into CODIS, an electronic database of DNA profiles. That process yielded a “hit,” identifying the defendant as the most likely source of the blood inside Molly’s room.

But will jurors be able to understand the expert’s intricate analysis and use it to reach a verdict? And what—if any—steps can be taken to increase jurors’ comprehension of complex DNA evidence? Questions such as these prompted an NIJ-funded study on the impact of jury trial innovations upon mock jurors’ understanding of contested mitochondrial DNA (mtNDA) evidence. By examining how jurors in different experimental conditions performed on a Juror Comprehension Scale both before and after deliberations, researchers were able to assess whether four specific innovations improved jurors’ understanding of this complex evidence and identify which innovations worked best.

Publication Citation

Published in: National Institute of Justice Journal, no. 255 (November 2006).