A new study re-uses some of the data collected for the Jury and Democracy Project, along with original complementary data, to show when juries herd together and when they remain divided. A team of researchers in California, Maryland, and North Carolina (Keith Burghardt, William Rand, and Michelle Girvan) analyzed jury outcomes with a focus on two variables–how long juries took to deliberate and how split they remained in their final judgment. Their findings now appear in a pre-publication article placed the sneaky-titled repository, arXiv. (It’s pronounced “archive.” There’s a “chi” in the middle. Get it? This is the kind of humor that gave rise to the other”Big Bang Theory.”)
The study focused on jury trials that do not require a unanimous verdict–in this case, a set of civil trials in a few states and criminal trials in Oregon, which has the distinction of supermajority decision rules for most types of criminal cases. In a nutshell, when juries strongly leaning toward the plaintiff/prosecution or toward defendant, they deliberate and reach a verdict rather quickly (less than three hours). When jurors’ views of the case are more evenly split, however, it’s much more likely they they will take 4-8 hours to deliberate.
As the authors put it, jurors’ inclination to render a near-unanimous verdict can lead to the quick verdicts, when the majorities start out large. Whether this is truly “herding” can’t be known, given the absence of data on jurors’ pre-deliberation leanings. More definitive is the label of juries as “stubborn” when they end up split, with jurors holding opposing views holding their respective ground.
From a distance, the findings aren’t altogether surprising, and they might be somewhat encouraging. They show that juries operating with supermajority decision rules operate efficiently, by reaching verdicts quickly when one appears clear at the outset. The findings could also be taken as another piece of evidence that only when given a unanimous decision rule do juries feel compelled to move more carefully through their deliberation, as “evidence-driven” rather than “verdict-driven” juries (to use the terminology popularized by Reid Hastie and colleagues’ classic, Inside the Jury).