Dateline: August, 2021, Issue 3
Expert witnesses testify in the vast majority of trials (see, for review, Jurs, 2016). Research conducted over three decades involving jurors in actual trials with expert testimony produces highly consistent results about what makes an expert witness persuasive to jurors.
In the 1990s, Champagne and colleagues (Champagne et al., 1991; Shuman et al., 1994) surveyed jurors about the characteristics necessary for an expert to be effective in court in four different cities. Jurors reported that the most important characteristics to make the expert believable are the expert's ability to convey technical information non-technically and the expert's willingness to draw firm conclusions.
In the 2000s, Ivković and Hans (2003) interviewed over 50 jurors from a variety of complex cases. While jurors preferred experts with quality credentials, the most common item mentioned by jurors was a clear presentation. Experts who appeared repeatedly for the same attorney, who used jargon, who were evasive, or who were inconsistent in their opinions were considered less credible.
In the 2010s, Jurs (2016) studied every civil case that went to trial in 2012 in Polk County, Iowa. Over 85% of the cases had at least one expert witness, and Jurs then surveyed the jurors in those cases about expert witness effectiveness. Jurors overwhelmingly (94%) reported that the ability to convey tecnical information in a non-technical fashion was the most important characteristic for an expert to have. Also important for an expert to have was being a leading expert in the field (81%) and a willingness to draw firm conclusions (72%). Jurors did not believe that an attractive physical appearance or pleasant personality were necessary. A huge majority of the jurors (98%) believed that experts are helpful to resolve legal disputes.
Communication skills -- clarity of presentation, conveying technical information non-technically, stating firm conclusions -- are critical for an expert to be persuasive to jurors. Qualifications and experience, while helpful, are not the most important factors that make an expert witness persuasive to jurors.
Source Champagne, A., Shuman, D. & Whitaker, E. (1991). An empirical examination of the use of expert witnesses in American courts. Jurimetrics, 31(4), pp.375-392.
Source Ivcović, S.K. & Hans, V.P. (2003). Jurors' evaluations of expert testimony: Judging the messenger and the message. Law & social Inquiry, 28(2), pp.441-482.
Source Jur, A.W. (2016). Expert prevalance, persuasion, and price: What trial participants really think about experts. Indiana Law Journal, 91(2), pp.352-391.
Source Shuman, D.W., Whitaker, E. & Champagne, A. (1994). An empirical examination of the use of expert witnesses in the courts -- part II: A three city study. Jurimetrics, 34(2), pp.193-208.