Katzev, R. D., & Wishart, S. S. (1985). The impact of judicial commentary concerning eyewitness identifications on jury decision making. The Journal of Criminal Law and Criminology, 76, 733-745.
A total of 108 students from Reed College in Portland, Oreg., were divided into 9 juries which viewed a 40-minute videotape of a mock trial involving a defendant accused of burglary. A key element in the prosecution’s case was the eyewitness testimony of a police officer and an innocent bystander. Each mock jury then heard various portions of an audio presentation of the judge’s instructions. Jurors were exposed to one of the following three conditions of judicial commentary: instruction only, instruction plus summation of the evidence, and instruction plus summation and commentary on the fallibility of eyewitness testimony. An overall chi square test revealed a marginally significant difference in predeliberation verdicts based on the information provided by the judge. The likelihood of a guilty judgment decreased with increasing degrees of information. Judicial comments to juries should enhance jurors’ understanding of the case without short circuiting the deliberation process. Judicial admonitions should encourage careful analysis of the relevant issues without producing an excessively cautious deliberative process. No impact of judicial post-trial comments on verdicts. Judicial summation of evidence resulted in shorter deliberation time; judicial summation plus evaluation of eyewitness credibility reduced time even further.