The spotlight finding of this massive study was that
judges and juries agreed on the appropriate verdict in
75.4% of the 3,576 criminal trials when hung juries
were treated as disagreements (and 78% of the trials
when they were distributed evenly between “agree” and
“disagree”). This figure for criminal jury trials was
remarkably close to the corresponding figure for the
approximately 4,000 civil jury trials for which data were
obtained in the same fashion. Criminal juries were
found to be more lenient than judges (i.e., they acquitted
when the judge would have convicted) in 19% of the
cases and more severe than judges in 3% of the cases.
Intensive analysis yielded five broad categories of
reasons for the discrepancies supplied by the judges:
(1) evidence factors, (2) facts known to the judge but not
to the jury, (3) disparity of counsel, (4) jury sentiments
about the defendant, and (5) jury sentiments about the
law. This research also produced a wealth of descriptive
data on juries that would serve as a benchmark for later
research, including estimates of the overall conviction
rate for juries (64%), the overall “win” rate for plaintiffs
(59%), and the frequency of “hung juries” (5.5%), as
well as profiles of the different types of evidence pre-
sented by the prosecution and the defense.
Another survey study associated with the project but
less well-known involved examining variation in dam-
age awards as a function of region. Six model cases
were created and submitted to 600 claims adjusters of
three large insurance companies operating throughout
the United States. Using the reports of claims adjustors
as a proxy for jury awards, this study anticipated the
now well-established finding that damage awards vary
considerably by jurisdiction and region.EExxppeerriimmeennttaall RReesseeaarrcchh WWiitthh MMoocckk JJuurriieess
After the commotion caused by the taping of actual
jury deliberations, project researchers were forced to
seek an alternative method for studying jury deliberation
and subsequently invented a staple methodology in the
jury-decision-making literature: the mock jury. Four dif-
ferent cases (or scenarios) were created for use with
mock juries to study the impact of manipulations asso-
ciated with, for instance, the weight of the evidence,
knowledge of the defendant’s insurance status in civil
cases, the legal definition of negligence in civil cases
(comparative vs. contributory) and insanity in criminal
cases, as well as the use of special verdict forms with
interrogatories. In the end, 160 mock civil juries
were run using two kinds of cases (auto negligence andproduct liability), whereas 98 mock criminal juries
heard either a burglary or an incest case. The research on
criminal juries was perhaps the first to show that an ele-
ment of the jury’s instructions (e.g, the definition of
insanity) could influence jury verdicts; in contrast, little
influence was associated with the provision of expert
testimony or the fate of the defendant. Despite the focus
on the effects of the manipulated independent variables,
this line of research is perhaps most notable for the
descriptive portrait it provided of jury deliberation. In
particular, this research suggested that forepersons were
usually selected quickly, with little discussion or cam-
paigning, and the choices could be explained well using
only three variables: prior jury experience, social status,
and seat position around the table. Another conclusion
was that speaking during deliberation was not egalitar-
ian, but rather, a small set of jurors tended to do most of
the talking (often males and those with more social pres-
tige), while some jurors typically said little or nothing.Project Legacy and Impact
It is common for scholarly papers on jury decision
making to reference the Chicago Jury Project, and it
is fair to ask if this exalted status is warranted. In
other words, what lasting impact has the project had
on the field of psychology and law? Arguably, the
project’s most fundamental contribution was in estab-
lishing the precedent that social science methods
could be used to understand and ultimately improve
the legal system. As natural and obvious as this may
seem today, there was nothing inevitable about it.
There are many institutions that have not received the
same attention from psychologists; for example, there
are no thriving subdisciplines for psychology and
government, psychology and medicine, or psychol-
ogy and the arts as there is for psychology and law. A
second contribution was in showing that the full spec-
trum of social science methods could be brought to
bear on the study of the legal system. Indeed, most of
the major methodologies used to study juries today
(with the exception of the Internet) were first used by
the Chicago Jury Project, and it also put the use of
mock juries on the map. Project researchers also
stumbled on the limits of the legal system’s tolerance
for social science methods via their seemingly
innocuous audiotaping of five civil jury deliberations
in 1955; the door to the jury room was literally closed
to researchers for basically the next 50 years (and it
is only now starting to reopen).Chicago Jury Project——— 67C-Cutler (Encyc)-45463.qxd 11/18/2007 12:41 PM Page 67