By Dr. Ken Broda Bahm:
I was recently assisting in a criminal jury selection. Over the course of several days, we moved through close to 50 potential jurors. I heard over and over again both sides’ efforts to acquaint the venire members with the standard of proof and to assess their willingness to follow it. “It isn’t ‘beyond a shadow of a doubt’ (the Perry Mason standard) the prosecution stressed, and “it isn’t ‘more likely than not'” (the civil standard) the defense countered. That sweet spot in between, “beyond a reasonable doubt,” was the focus. Do the potential jurors understand what that means? Are they willing to follow the standard in this case?
Unfortunately, based on the limits of questioning in voir dire, that is not something that can be assessed based on a professed willingness. No matter how many potential jurors say they understand and promise to follow, it is an empirical question: Will they? More broadly, will average people actually decide any differently based on the legal standard they are asked to follow? The question has been studied over the years with some mixed results. But a new study (Davis, 2013) applies a different methodology to the question and casts substantial doubt on the assumption that standard of proof makes much of a difference in how jurors are likely to decide. This post takes a look at that research and what it means for teaching the right standard of proof to your jury.
The Study: Do Jurors Rule Based on Standard of Proof?
No, they don’t. Not really, or at least not when it matters most. That is the conclusion of Florida State University behavioral economist Brent Davis in this recent study. The results do conflict with some research showing very small differences in the right directions (for example Glöckner & Engel, 2013). But Davis’ method was unique in several respects. Most importantly, his study represents the first true incentivized simulation of jurors’ decision making under varying standards of proof. What that means is detailed here in the study’s write-up.
Method
I won’t fully describe the method here, because it is involved and a little bit hard to follow, but a few features of the method are important.
It simulates and doesn’t just describe. Instead of just asking study participants to react to static case descriptions as most similar studies do, Davis creates a game scenario that involves plaintiffs, defendants, jurors, and alternates. The game involves one player reporting a number to another player, creating the possibility for bluffing. In the event that one player feels misled, they have the option to bring the matter to trial. The defendant, then, faces the accusation of reporting incorrect information and they may actually be innocent or guilty.
It creates incentives. In most studies, when participants cast their vote on a paper scenario, they know or suspect their vote will not truly affect real parties in any real situations. Davis’ study, however, is incentivized in the sense that it builds in monetary consequences for the parties who win or lose. Participants lose or gain moderate dollar amounts as a result of the jury’s verdict. Part of the manipulation of the study was to make those consequences higher or lower.
It measures binary and relative evaluations. Juror participants were asked to provide an estimate of guilt on a zero to one hundred scale, and also to case the yes/no verdict on guilt. That method allowed the researcher to note where individuals placed their threshold under different standards of proof.
There are several other elements of the study which also focused on the behavior of the plaintiff and defendant in choosing to go to trial or not, but for my focus on the role of standard of proof, those are the key takeaways. So what did the study find?
Results
Not much difference. The assumption is that raising the standard of proof raises the threshold for a decision. But in the simulation, asking participants to apply a reasonable doubt or a preponderance standard resulted in only a “mild response” which was not statistically significant overall.
Only matters in low consequence situations. The exception applied to situations where the consequences of a win or a loss were low. “There were significant differences in conviction rates between reasonable doubt and preponderance of the evidence,” Davis noted, “however, this only occurs in the low consequences treatment.” That seems counterintuitive, of course, but the author reasons that when consequences are low, the decision makers may be less sensitized to the consequences of conviction, and thus more likely to reconcile a consistency between their beliefs about probability of guilt and the legal standard they’re asked to follow. In any case, when the consequences are higher — as they would be in real legal cases — the application of different standards of proof does not create a reliable difference in decision making.
No clear threshold. The point of articulating a standard is to identify a definite threshold or tipping point in the decision. That threshold, however, was not found in the data when plotting the percentage found guilty against a juror’s zero to one hundred estimate of likelihood of guilt. “Jurors do no have a universal threshold for guilt amongst preponderance of evidence or reasonable doubt,” the author concluded, “but instead have a threshold individual to each case.”
The Recommendations: Adapt to the Uncertainty of Jurors’ Standard
Of course, neither litigators nor judges can just give up in emphasizing burden of proof. The standard still has to matter, but it cannot be handled by simply repeating it and eliciting a promise from jurors that they understand and will follow it. The lack of support for a measurable difference being made by the standard of proof is probably due to the fact that the standards are abstract. As jurors in a civil case, for example, move from “preponderance” to “clear and convincing” for a particular claim on malice, what has actually changed? In their earlier negligence decision, would they have really voted “yes” if they had thought it was not clear or convincing? The bottom line is that legal persuaders need to try to give these words a real meaning beyond a simple reading. That suggests a few things.
Operationalize Burden of Proof in Terms of Your Case
You can define a standard like reasonable doubt and leave it at that, or you can apply it specifically in the context of your own case evidence. A prosecutor, for example, might say the following in closing:
We’ve talked about the standard of reasonable doubt, and the defense has talked a lot about doubt. But when does a doubt become reasonable in this case? “Reasonable” isn’t just a word that means “maybe.” It means something that can be supported by reasons. Let’s take the eye witness. Is it possible to think she is making it all up for an unknown reason? I guess, “possible” is a big word. But is there a reason to think that’s true? No, you haven’t heard one. So there is no reasonable doubt on this point.
Use Burden of Proof as a Tiebreaker
The specific standard may not be the target you’re aiming at throughout the case, but it can still play a role at the final point of a jury’s decision making. We see that dynamic often when watching juror deliberations in a mock trial. Jurors will not all be in the same place and will look for some kind of tool of compromise. Some might be raising doubts about a civil defendant’s behavior, when another brings up the standard of proof as a way of saying “We can both be right: You’re right that there are concerns, but we’re right that they don’t rise to the level.” In that way, the burden can work like a bucket for the jury’s uncertainties.
Always Aim to Prove at the Highest Level
Litigators should not create a burden of proof where they don’t have to. But one takeaway of the research is that they shouldn’t rely on the false precision of a specific legal standard either. Instead, it helps to always aim to exceed the standard, making everything “clear” and “convincing” whether the legal standard says it has to be or not. David Ball, one of the co-creators of the Reptile perspective on advocacy, for example, has commented that in practice the safety-driven standard of proof in a criminal case boils down to “could have done it.” Of course, that isn’t always the case, and the Casey Anthony decision stands among others as examples of strong burden of proof-driven verdicts. But criminal defendants are better off if their aim is to create a probability in jurors’ minds they they didn’t do it, and not just a reluctant admission that the state did not prove their case.
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Other Posts on Burden of Proof:
- Keep Your Burden of Proof in Your Back Pocket
- Go for “Mad” Not “Sad” When You’ve Got the Burden: Listening to Juror B37
- Address Fundamental Skepticism on Rule of Law
- Take a Lesson from the Casey Anthony Verdict: It Is the Story, and Not Just the Evidence
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Davis, B. J. (2013). Standards of proof and quantitative differences in juror convictions and beliefs in an incentivized experiment. Florida State University, Department of Economics:
Photo Credit: Hades2k, Flickr Creative Commons