Dateline: November, 2007, Issue 3

Do larger or smaller juries perform better?

Some cases, courts and jurisdictions rely on juries smaller than 12 persons. At times, litigants give permission to continue a trial with fewer jurors than originally selected. Jury size affects jury decisions, and whether a smaller or larger jury is preferred in any given case depends on the nature of the case, the strength of the evidence, the degree to which deliberation is desired, and a host of other factors.

Zeisel (1971) published some of the earliest research examining jury size, finding that 6-person juries perform worse when recalling the evidence, are less representative of the community, are more variable in awards, and less likely to deadlock.

In 1997, Saks and Marti combined data from 17 individual studies over a multiple-decade time period involving 2,061 juries and over 15,000 individual jurors, and reported similar results. Larger juries were more likely than smaller juries to contain members of minority groups, deliberate longer, hang more often, and recall trial testimony more accurately.

Recently, Horowitz and Bordens (2002) examined evidentiary discussions and punitive damage awards of 6- and 12-person juries. Compared with larger juries, the punitive damage awards of 6-person juries were highly variable, meaning that some were very much larger and some were very much smaller than those of 12-person juries. Said differently, the punitive damage awards of 12-person juries were more predictable than of 6-person juries. Larger juries also deliberated longer, recalled more probative information, and relied less than smaller juries on nonprobative evidence.

In sum, larger juries are more accurate and probative in their evidentiary discussions, and more likely to deadlock, while smaller juries are less predictable (more variable) in their damage awards, less accurate in their evidentiary discussions, and less prone to hang.

Source Zeisel, H. (1971). And then there were none: The diminution of the federal jury. University of Chicago Law Review, 38, pp. 710-724.

Source Saks, M. J. & Martie, M. W. (1997). A meta-analysis of the effects of jury size. Law and Human Behavior, 21, pp. 451-467.

Source Horowitz, I. A. & Bordens, K. S. (2002). The effects of jury size, evidence complexity, and note taking on jury process and performance in a civil trial. Journal of Applied Psychology, 87, pp. 121-130.