Encyclopedia of Psychology and Law

report comes after, whether the judge has been

affected by that knowledge. Nonetheless, the case-

based judicial survey ensures that the judge and jury

verdicts being compared come from equivalent cases

because the judge in each case is providing a judicial

verdict in precisely the same real trial that a jury

decides. The judge and jury in the Kalven-Zeisel sur-

vey of 3,500 criminal cases agreed in 78% of the

cases on whether or not to convict. When they dis-

agreed, the judge would have convicted when the jury

acquitted in 19% of the cases, and the jury convicted

when the judge would have acquitted in 3% of the

cases—a net leniency rate of 16%. Disagreement

rates were no higher when the judge characterized the

evidence as difficult than when the judge character-

ized it as easy, suggesting that the disagreements

were not produced by the jury’s inability to under-

stand the evidence. Disagreement rates did rise when

the judge characterized the evidence as close rather

than clear, indicating that disagreement cases were, at

least in the judge’s view, more likely to be those cases

that were susceptible to more than one defensible

verdict. Primary explanations offered for the overall

differences were differences in judgments about the

credibility of witnesses and a different threshold of

reasonable doubt. Two smaller, more recent studies

using the Kalven-Zeisel method have shown remark-

ably similar patterns in criminal cases, obtaining 74%

to 75% agreement, with a greater leniency of 13%

to 20% from the jury. Studies outside the United

States have shown similarly high levels of agreement

between professionals and juries or lay judges in

criminal cases.

For the 4,000 civil trials in their judicial survey,

Kalven and Zeisel obtained the same agreement rate

of 78% on liability, but disagreement was almost

equally divided, so that in 12% of the cases, the jury

found for the plaintiff, while the judge favored the

defense and in 10% of the cases, the jury found for the

defense, while the judge would have made an award.

Awards by juries were 20% higher on average than

awards by judges. Several smaller, recent studies of

civil jury cases in several locations have indicated

agreement rates on liability between 63% and 77%,

but it is unclear whether any overall change has

occurred over time because no national study compa-

rable with the Kalven and Zeisel study has been con-

ducted. Because punitive damages are awarded so

rarely (in roughly 3% of contract and tort cases),

researchers conducting case-specific judicial surveys

have not been able to compare judge and jury deci-

sions on punitive damages.

Simulations and Experiments

A third approach comparing judge and jury decision

making asks judges and laypersons to reach decisions

based on simulated trial materials in the form of written

materials or videotaped presentations. Comparability is

ensured by having the judges and laypersons read or

view precisely the same stimulus. In addition, by exper-

imentally varying the stimulus within each group,

researchers have tested how specific variations in the

evidence (e.g., exposure to inadmissible evidence) affect

judges and laypersons differently. The extent to which

these simulated decisions reflect what the decision mak-

ers would do in a real trial is contingent on the extent to

which the simulation captures the relevant factors that

would affect trial judgments. The materials in these

studies generally must be brief to obtain judicial partic-

ipation. Trial elements such as jury instructions are often

truncated or missing. Mock jurors frequently are not

asked to deliberate, so that the judicial responses are

compared with those of individuals rather than the

group decisions of multiple jurors. Nonetheless, the few

experiments comparing judges and laypersons reveal a

striking overall similarity between their decisions.

Experiments showed that exposure to inadmissible

evidence influenced judges and laypersons similarly,

and both groups were reluctant to impose liability

based on mere statistical evidence. In several experi-

ments involving personal injury cases, both profession-

als and laypersons responding to the same cases used

the severity of injury in determining pain and suffering

awards, but in one study, laypersons were more variable

in their awards. It is unclear how much, or whether,

variability in decisions by lay decision makers would

drop if their awards were determined by group verdicts

rather than individual judgments. In determining crim-

inal sentences in a series of cases, laypersons favored

lower penalties than judges did, indicating that the

same greater leniency was shown by juries in criminal

conviction cases in case-based judicial surveys.

In a few of the experiments directly comparing the

judgments of judges and laypersons, the samples

tested raise questions about the representativeness of

the findings because the laypersons were students or

the judges sampled came from a unique subgroup

(e.g., those who had signed up to attend a law and

economics seminar). Much more research is needed to

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