Juror Certainty about Expert Firearms Identification Evidence and the Impact of Cross-examination

Paraic Scanlon, Boglarka Banyai, Ellis Hart, Sarah Lucy Cooper

    Research output: Contribution to journalArticlepeer-review


    To evaluate association, firearms examiners compare tool-marks present on suspect ammunition to those present on ammunition test-fired by a suspect weapon. Examiners? conclusions are generally admissible in US courts, yet the scientific underpinnings of the discipline have been subject to considerable criticism. Cross-examination can be used to bring such criticism to the attention of jurors, who determine the weight of expert evidence. The authors investigated the effect of such cross-examination on juror certainty about expert firearms evidence using online vignettes. A community sample of US participants (n=437) were asked to rate their certainty (0-100) of a forensic match for each of 4 expert statements of certainty, in 2 groups; either with or without a cross-examination highlighting limitations of the tool-mark discipline?s scientific underpinnings. Analysis was undertaken both between groups and between the statements given to each group. Results suggest that cross-examination can have a strong influence on juror decision-making, particularly when experts express their conclusions in certain terms.
    Original languageEnglish
    JournalSouthern California Interdisciplinary Law Journal
    Publication statusPublished (VoR) - 21 Jun 2021


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