Jury verdicts: The role of group size and decision rule.

Saks, M. (1977). Jury verdicts: The role of group size and decision rule. Washington, DC: Lexington Books.

WHENEVER WE CONSIGN TO A GROUP THE ROLE OF DECISION MAKING, WE OBLIGATE OURSELVES TO MAKE CHOICES CONCERNING AT LEAST TWO STRUCTURAL FEATURES OF THAT GROUP: ITS SIZE AND THE SOCIAL DECISION RULE (SDR) THAT WILL DEFINE GROUP CONSENSUS. JURIES HAVE TRADITIONALLY OPERATED WITH A GROUP SIZE OF TWELVE AND A SDR OF UNANIMITY. BOTH THESE FEATURES HAVE RECENTLY BEEN CALLED INTO QUESTION, HOWEVER. IN THE SUPREME COURT’S MAJORITY AND DISSENTING OPINIONS IN THE CASES CONCERNING JURY SIZE AND SOCIAL DECISION RULES, A NUMBER OF EMPIRICAL QUESTIONS WERE DEBATED. THE AUTHOR REVIEWS THESE BEHAVIORAL ISSUES, AND POINTS OUT SOME ADDITIONAL ISSUES THAT THE JUSTICES DID NOT RAISE. HE THEN REVIEWS AND CRITIQUES A NUMBER OF EMPIRICAL RESEARCH STUDIES PROMPTED BY THE SUPREME COURT’S DECISIONS IN SUCH CASES AS WILLIAMS V. FLORIDA, JOHNSON V. LOUISIANA, AND APODACA V. OREGON. THE TWO STUDIES REPORTED IN DEPTH IN THIS TEXT WERE DESIGNED TO EXAMINE THE EFFECTS OF VARYING GROUP SIZE AND SOCIAL DECISION RULES ON GROUP PROCESSES AND DECISIONMAKING IN THE CONTEXT OF JURY DELIBERATIONS. THE TWO EXPERIMENTS ARE IDENTICAL TO EACH OTHER EXCEPT THAT THE FIRST USES UNDERGRADUATE STUDENTS AND A WRITTEN TRANSCRIPT, WHILE THE SECOND USES REAL JURORS AND A VIDEOTAPED TRIAL. THE RESULTS SHOWED THAT NO ONE JURY TYPE CAPTURES ALL ADVANTAGES AND DESIRABLE CHARACTERISTICS. SPECIFIC ADVANTAGES OF EACH TYPE OF JURY — SIX- AND TWELVE-MAN, UNANIMOUS AND QUORUM VERDICT — ARE NOTED, AND BASED ON THESE FINDINGS, THE AUTHOR SUGGESTS A NOVEL JURY STRUCTURE THAT COMBINES THE BEST FEATURES OF EACH JURY TYPE. Participation rate more equal in 6-person juries; certainty of guilt greater for convicting juries under unanimity rule. <1>No impact of jury size or decision rule on verdicts, deliberation time, or recall of testimony. <2>Unanimous juries hung more often. Larger juries deliberated longer and members recalled testimony better; members of smaller juries recalled higher percentage of arguments generated. Evidence of “2/3 majority otherwise hung” SDS.

https://www.ncjrs.gov/App/publications/abstract.aspx?ID=42103