Academics and Research

Law school faculty pioneer research on jury behavior

Long before summoned to duty, long before seated in the box, the anonymous juror figures prominently in day-to-day legal proceedings.

When a suit is filed, when settlements are negotiated, when attorneys advise their clients about the chances of a favorable court decision, their first thoughts go to the jury. Just how will it decide?

So what do today’s attorneys know about the science — in addition to the art — of persuading jurors?

Not nearly enough, say Bernard Chao and John Campbell of the Sturm College of Law. Together they’re seeking to remedy that through a series of studies that employ social science methodologies to demystify, as Chao puts it, “the ways that jurors react to particular types of tactics and arguments.”

How, for example, do jurors respond when attorneys in product liability cases “anchor” their requests for damages with a range of sums? How do they react when opposing attorneys ridicule those demands or counter with another sum? And what happens when a judge tells jurors to disregard a certain bit of testimony?

As Chao and Campbell see it, this is critical information for trial attorneys, but it has long been in short supply. They know this from personal experience. Before joining the Sturm faculty, Chao, now an associate professor, spent several years representing defendants in patent law cases, while Campbell, an assistant professor of practice, worked for one of the country’s largest plaintiffs firms, representing individuals in cases against businesses. From their vantage point in the courtroom, both watched juries grapple with complex arguments from attorneys and often perplexing instructions from judges.

“I had been interested in behavioral psychology with respect to juries for a while,” Chao recalls, noting that his understanding of juror response to courtroom presentations, though rooted in firsthand experience, was purely theoretical. Surely, he surmised, his theories and suppositions could be supported or contradicted by science.

Campbell, meanwhile, was riding the same train of thought. “I was thinking constantly about how [solid data] would be so useful in law and how little it is used,” he recalls. “I knew in our firm that a lot of big decisions — cases where tens of millions of dollars or hundreds of millions of dollars [were at stake] — were made based on instinct, based on what you’d heard from other attorneys or based on what you’d done twice and it had worked. In other fields, that would have been considered insane.”

To date, Chao and Campbell have conducted two studies and begun work on a third. Their first study focused on how, with the jury in mind, defendants should respond to the common plaintiffs’ tactic of “anchoring” damage requests. Anchoring, Chao explains, occurs when plaintiffs suggest suitable awards to jurors. The other study looked at the impact of per diem arguments on pain and suffering awards. Per diem arguments show the jury just how an attorney arrived at a suggested damage amount — by, say, calculating the likely number of days and years the individual in question will be affected, assigning a “wage” to each day and then completing the math.

The findings of the Chao/Campbell studies are shared at the Sturm-based Denver Empirical Justice Institute, launched by the two professors to further their interest in legal research. The full results of their first study will also be published in a forthcoming issue of the Iowa Law Review, one of the country’s most reputable legal journals.

That their fledgling work is getting this kind of attention suggests the need for such research. Up until now, Chao points out, lawyers seeking to understand jury behavior have had to rely on a handful of studies constrained by budgets and feasibility. Now, thanks to the Internet and its ability to connect researchers with vast pools of study participants, jury research can be conducted quickly and inexpensively.

Here’s how the Chao/Campbell studies work: “We videotape a trial, then shorten it to 35 or 40 minutes. [We film] actual witnesses, judges giving instructions, lawyers giving opening and closing arguments,” Chao explains.

Then, with the help of a crowd-sourced platform from called Mechanical Turk, various versions of the videos are shown to distinct sets of mock jurors, who are asked to arrive at verdicts and awards. By varying the videos for each pool of jurors just slightly, by modifying a few seconds here and there to include different instructions from the judges or to alter the proposed size of an award, they can gauge the effectiveness of certain tactics.

Although the studies don’t account for the effect of deliberations on a jury’s final decision, they do indicate how jurors are leaning before they meet to discuss the case. In their first study, the pair learned that a simple eight-second variation in a closing argument could have a dramatic effect on damages. In fact, Chao notes, a slight deviation in strategy increased damages by about 800 percent.

Information like this can do more than help trial lawyers craft their courtroom presentations. It can also pave the way for settlements and keep cases out of the courtroom, Campbell explains.

“Everything is negotiated within the shadow of the jury room,” he says, noting that if attorneys preview their arguments before virtual jurors and learn how they’re likely to decide, that could persuade a client to settle or even to drop a case — thus saving everyone, taxpayers included, a lot of time and money.

As Chao and Campbell see it, these studies are not just useful for trial lawyers; they’re also potentially helpful for judges. For example, a study might show that a judge’s limiting instructions — which tell jurors how to use evidence — are counterproductive. In other words, a judge’s call to disregard a particular piece of evidence might actually highlight that evidence in the juror’s mind. If that’s the case, judges might reconsider the practice.

“Judges might be giving instructions to juries that actually make things worse, but they do it because they think they should, because that’s how people should act,” Campbell says.

“But,” he adds, “the law shouldn’t be having jury trials based on what we hope juries will do. It should be based on what juries actually do.”

The Denver Empirical Justice Institute is sponsoring a one-day conference, “The Art and Science of Persuading Jurors,” on Wednesday, Feb. 24. To learn more, contact John Campbell at


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