Jurors’ Perceptions of Evidence: The Relative Influence of DNA and Eyewitness Testimony when Presented by Opposing Parties

Abstract

Previous research has compared the relative influence of DNA evidence and eyewitness testimony on mock jurors’ decisions, but always when presented by the same litigating party. The current study sought to test whether jurors would be more persuaded by DNA evidence than testimony from an eyewitness when these two forms of evidence were presented by opposite sides, and whether evidence strength would interact with type of evidence to affect verdict decisions and evidence ratings. Participants read a trial transcript in which either the Crown presented DNA strong/weak evidence while the Defence presented strong/weak eyewitness evidence, or vice-versa, then provided a verdict and evidence ratings. Results revealed that DNA evidence yielded more verdicts in favour of the party presenting it, but that contrary to some earlier research, jurors were somewhat sensitive to the differences between strong and weak DNA evidence. Interestingly, the strength of eyewitness evidence affected participants only when it was presented by the Crown. Attitudes toward each type of evidence were unaffected by evidence strength or presenting party, suggesting that these attitudes are stable.