Jury decision making: 45 years of empirical research on deliberating groups.

This article provides a comprehensive review of the empirical research on jury decision making published between 1955 and 1999. In total, 206 distinguishable studies involving deliberating juries (actual or mock) were located and grouped into 4 categories on the basis of their focal variables: (a) procedural characteristics, (b) participant characteristics, (c) case characteristics, and (d) deliberation characteristics. Numerous factors were found to have consistent effects on jury decisions: definitions of key legal terms, verdict/sentence options, trial structure, jury—defendant demographic similarity, jury personality composition related to authoritarianism/dogmatism, jury attitude composition, defendant criminal history, evidence strength, pretrial publicity, inadmissible evidence, case type, and the initial distribution of juror verdict preferences during deliberation. Key findings, emergent themes, practical implications, and future research directions are discussed. The petit jury is a well-known component of the U.S. legal system that needs little introduction. More than 150,000 jury trials take place each year in the United States ( Landsman, 1999 ; Saks & Marti, 1997 ), and tens of thousands more in other countries throughout the world. Hundreds of thousands of U.S. citizens serve on juries each year and a sizable percentage of the population will do so at some point in their lives. The jury system has been around for hundreds of years and it is considered a cornerstone of democracy ( Abramson, 1994 ). Despite frequent criticism (see Penrod & Heuer, 1998 , for a review), it has proven to be a remarkably resilient institution. Although juries have been used in the United States since its founding, scientific interest in jury decision making is a relatively recent phenomenon. Isolated studies were conducted before World War II (e.g., Weld & Danzig, 1940 ), but systematic research on juries did not begin until 1953 and the initiation of the Chicago Jury Project. This multiyear effort was undertaken by a team of researchers at the University of Chicago and financed by two large grants from the Ford Foundation ( Ellsworth & Mauro, 1998 ).