Chicago Jury Project

The Chicago Jury Project was a large-scale social science research initiative in the 1950s. This research paper provides a descriptive portrait of the project, followed by a brief summary of the primary studies associated with it, and then a discussion of the project’s legacy and its impact on the field of psychology and law. In essence, the Chicago Jury Project was a groundbreaking scientific endeavor that employed a variety of social science methods and anticipated a host of current research streams. It remains an impressive accomplishment and can fairly be said to represent the inaugural event in the scientific study of jury decision making.

Chicago Jury Project Overview

The Chicago Jury Project, also known as the American Juries Project, was conceived as an innovative effort to study the American legal system using behavioral science methods. Initiated in 1953 with funding from a $400,000 grant from the Ford Foundation, the project was housed at the University of Chicago. A variety of research studies were undertaken with the aid of project funding, not all of which were concerned with juries (e.g., arbitration). The project was led primarily by three individuals: Harry Kalven (a law professor), Hans Zeisel (a sociologist, statistician, and law professor), and Fred Strodtbeck (a social psychologist), although more than 20 other individuals were affiliated with the project, including Dale Broeder and Rita James Simon. The initial funding was spent by 1956, which triggered a review of project activities and findings by the Ford Foundation. A second round of funding from Ford enabled some arms of the project (most notably the work on juries) to continue until 1959, at which point active data collection ceased. A bibliography published in 1966 listed more than 60 journal articles published by researchers associated with the project. In-depth summaries of selected project initiatives were subsequently published in three book-length volumes titled Delay in the Court (1959), The American Jury (1966), and The American Jury: The Defense of Insanity (1967). The physical records of the project are currently held in 10 boxes at the Special Collections Research Center at the University of Chicago’s Law School.

Few social science research projects receive public attention, and even fewer achieve any that is sustained, but the Chicago Jury Project actually caused something of a national scandal at one point in its existence. One early initiative involved audiotaping the deliberations of five civil jury trials in the federal district court in Wichita, Kansas. Although this was done with the assent of the trial judge and counsel for both sides, the jurors were unaware that their discussion was being recorded. When this became public knowledge in the summer of 1955, uproar ensued. The methodology was publicly censured by the Attorney General of the United States, a special hearing was initiated by the Senate Judiciary Committee, and more than 30 jurisdictions subsequently enacted statutes prohibiting the direct observation or recording of jury deliberations.

Chicago Jury Project Studies and Results

As noted above, the Chicago Jury Project consisted of a number of different research initiatives involving several major methodological strategies: (a) analysis of archival data on court system functioning, (b) surveys, (c) intensive interviews with attorneys and jurors, and (d) experimental research with mock juries. This section briefly summarizes the project activities and findings within each methodological domain.

Archival Research

Much of the early work associated with the project involved taking stock of the descriptive research already done by others. One line of inquiry was comparative in nature and attempted to identify what had been learned about legal systems in general and the jury in particular in Western Europe. An effort was also made to collect and examine jury trial statistics from several major metropolitan areas in the United States in order to estimate the frequencies associated with defendants’ waiving their right to jury trial, the occurrence of hung juries, and the number of annual jury trials in the United States. Existing data were also gathered on the extent to which judges agreed with the verdicts of their juries as well as the nature of cases heard by judges and juries. In the end, this archival research set the stage for a number of later project activities and produced the following conclusions: (a) there did not exist much data on juries outside the United States; (b) defendant waiver rates varied considerably across jurisdictions within the United States; (c) criminal “hung jury” rates varied across jurisdictions but on average occurred about 5% of the time; (d) judges and juries agreed on the appropriate verdict in about 75% to 85% of cases; (e) when trial complexity was taken into account, juries were about on par with judges in terms of the time needed to resolve cases; and (f) about 55,670 jury trials occurred in the United States in 1955 (which is considerably higher than current estimates).

Interview Research

Researchers associated with the Chicago Jury Project made extensive use of interview methodology in the course of their work. One notable study involved having one of the project researchers (Dale Broeder, a law professor) accompany a federal district court judge on his circuit for the better part of a year. During this time, he conducted intensive interviews with 225 jurors and many of the attorneys involved in 20 jury trials. Attorneys were asked about their strategies during voir dire and their reasons for challenging particular jurors; jurors were questioned about their attitudes toward the jury system in general, their service, and their preferences for particular kinds of trials. One finding from this line of work was that many jurors were not looking to serve, but those that did tended to be positively influenced by their experience and more supportive of the jury system afterward. This labor-intensive endeavor resulted eventually in a number of essays highlighting commonalities in deliberation across cases, most of which were published in law journals.

One of the most well-known findings associated with the Chicago Jury Project arose from a massive field study featuring interviews with more than 1,500 jurors from 225 criminal jury trials in Chicago and Brooklyn. Among the goals of this study was reconstruction of the distribution of juror votes on the first ballot taken during deliberation. The result—surprising at the time but often replicated since—was that the verdict preferred by the majority of the jury on the first ballot ended up being the jury’s final verdict approximately 90% of the time regardless of the demographic composition of the majority and minority factions. Furthermore, the minority factions that did manage to prevail were typically fairly large (i.e., three or more jurors), not lone “hold-out” individuals. Project researchers concluded from this that most criminal cases were decided during the trial as opposed to deliberation, and they likened deliberation to the role of the dark room in photography—the image (verdict) was set at the moment of exposure (i.e., the conclusion of the trial), but deliberation served as the developmental process that brought the image to light. This line of work also produced some interesting generalizations about juror voting preferences as a function of ethnic/national background, as well as some of the first empirical evidence that jurors do not always fully understand their instructions.

Survey Research

Perhaps the most famous research associated with the Chicago Jury Project, however, concerned the extent to which it makes a tangible difference to the outcome whether bench trials or jury trials are used. To examine this question, project researchers assembled a comprehensive listing of judges who presided over jury trials and then invited all the 3,500 or so individuals on the list. In the end, 555 trial judges from every state (except Rhode Island) as well as the federal courts participated. Essentially, the participating judges were asked to fill out a brief questionnaire for each jury trial they presided over during the study and return it by mail. Sample I was collected during 1954 to 1955 using the first version of the questionnaire (k = 2,385 trials); Sample II was collected during 1958 using a revised and elaborated form (k = 1,191 trials). Although additional information was collected (especially on the second form), the focus was on three things: (1) the jury’s actual verdict, (2) the judge’s indication of what he or she thought was the appropriate verdict, and (3) the judge’s perceived reasons for any discrepancy between the first two.

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 presented by the prosecution and the defense.

Another survey study associated with the project but less well-known involved examining variation in damage 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.

Experimental Research with Mock Juries

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 different cases (or scenarios) were created for use with mock juries to study the impact of manipulations associated 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 and product 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 element 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 campaigning, 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 egalitarian, but rather, a small set of jurors tended to do most of the talking (often males and those with more social prestige), while some jurors typically said little or nothing.

Chicago Jury 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 establishing 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 psychology and the arts as there is for psychology and law. A second contribution was in showing that the full spectrum 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).

Other lasting contributions associated with the Chicago Jury Project include the initiation of research on a remarkably diverse set of legal topics, devoting attention to civil as well as criminal juries, using a multidisciplinary approach with individuals from various fields, and publishing project findings in legal as well as psychology journals. By any standard, the number of publications resulting from the project’s work is impressive, and there is no doubt that their widespread dissemination in different outlets is a major reason why the Chicago Jury Project is still so well-known today. These publications provided a number of descriptive findings based on large samples that provided empirical benchmarks for later work, including estimates of the frequency of jury trials, hung juries, and judge-jury agreement and a first por-trait of deliberation that included foreperson selection and the power of early majority.

Alas, one unfortunate aspect of the project may have stemmed from the fairly cynical view of deliberation offered in The American Jury (1966). The colorful yet deterministic “dark room” metaphor may have inadvertently dissuaded a generation of jury scholars from taking an active interest in the dynamics of deliberation, and in some respects, it may continue to dampen interest in what happens behind the closed door of the jury room. Nonetheless, even 50 years later, the scope and accomplishments of the Chicago Jury Project remain remarkable, and it truly deserves its lustrous reputation as a seminal event in the field of psychology and law.


  1. Broeder, D. (1958). The University of Chicago Jury Project. Nebraska Law Review, 38, 744-760.
  2. Kalven, H., Jr., & Zeisel, H. (1966). The American jury. Boston: Little, Brown.
  3. Simon, R. J. (1967). The jury and the defense of insanity. Boston: Little, Brown.
  4. Strodtbeck, F. L., & Lipinski, R. M. (1985). Becoming first among equals: Moral considerations in jury foreman selection. Journal of Personality and Social Psychology, 49, 927-936.
  5. Zeisel, H., Kalven, H., Jr., & Buchholz, B. (1959). Delay in the court. Boston: Little, Brown.

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