To many trial-watchers, a key moment in the recent trial of former Minneapolis police officer, Derek Chauvin, for the murder of George Floyd, came during the testimony of Dr. Martin Tobin. This Chicago pulmonary physician, in plain language and a mild accent from his native Ireland, testified about Mr. Floyd’s last minutes and pinpointed the moment and the cause of his death. Explaining the effects of neck compression, Dr. Tobin demonstrated the anatomy using his own neck, and many jurors followed that example, touching their own necks. The influence of that moment of clear explanation and participation was confirmed this week as the first juror in the trial opted to speak publicly.

Brandon Mitchell, a high-school basketball coach and podcaster, was Juror 52, one of the twelve who reached unanimous guilty verdicts against Derek Chauvin on all three counts. In his first television appearance on Good Morning America, Mr. Mitchell identified this as the key moment in his persuasive process: “Once Dr. Tobin got on the stand, that really solidified the case.” In an interview with CNN, he went on to say that by the time that testimony was finished, “I felt like the trial was done. He spoke everything in laymen’s terms, and it made sense.” In any trial with complex testimony, clear explanation is essential, but a moment of participation can seal the influence of that testimony. In other words, it helps if you can find a way for your audience to participate in the process. In this post, I will take a brief look at the reasons participation helps persuasion, and how it can work in court.

Participation Aids Recall and Belief…

I once monitored an extended and complex products liability case focused on agricultural contamination. Working for the plaintiffs in that case, we had one expert whose job it was to explain the particular kind of bacteria that this chemical caused to grow out of control. It was pretty complex biochemical content. But just like your favorite middle school science teacher, our expert was able to make the explanation engaging. It was our good luck that this particular bacteria glowed under a black light, so when the expert rigged some cardboard light boxes, we were able to get the judge to agree to having the jurors come out of the jury box and peer into each of the boxes in order to see the growth and proliferation of the bacteria.

Now, why did this aid the testimony? Well, first, it is guaranteed that they will remember it. It broke up the tedium of scientific testimony, and the boredom of just sitting and listening. But second, and more subtly, experience also increases the perceived veracity of the information. That is, when the jurors remember it, they remember it in the context of their own actions, even if the actions are as simple as getting out of their chairs and peering into a box. The fact that their recollections are tied to their own agency creates the feeling that it is their own knowledge, and not just something they received from somewhere else. Not only do they remember it more, they also own it to a greater degree.

Even When it is not Probative…

It is safe to say that the fact that the bacteria glowed — the only thing we were actually showing in that demonstration — did not really add to the proof in the case. It simply made the testimony more personally memorable, and that made it more likely that jurors would retain and use the testimony, including the parts that were probative.

It is likely that Dr. Tobin’s testimony in the Chauvin trial worked in the same way. The anatomy of the neck aided the proof in that case, but was not proof by itself. Jurors were more likely to remember examining their own necks, which probably made it easier and more personally salient to remember the testimony more generally.

Now, some purists might object that if a demonstration like that isn’t really probative, then it has no place in a courtroom. I think that goes too far. An adversary system like ours is tied to the goals of communication, so we accept that not everything is going to add logical proof. A witness looking professional, using clear language, and not insulting the court — that’s also not probative, but they’re all definitely good ideas. So too is the device of using tools like participation to make an explanation more accessible and more memorable. It is part of the process of putting the facts in the best light.

One Side Note:

Changing the subject just a bit while we are still on the Chauvin trial, there is one instance, also coming from the recent juror interview, where non-participation seems to have been probative: Derek Chauvin exercised his right not to testify and did not take the stand in his own defense. Asked whether this mattered to the jury, Mr. Mitchell gave the answer every criminal defendant dreads: “It really did [matter]. It probably was to his detriment that he didn’t take the stand, because people were curious on what his thoughts were throughout the entire incident.” This jury was clearly instructed to draw no adverse inference from the absence of that testimony, but it is inevitable that this absence created a gap that could not be filled.

I understand the conventional wisdom that a defendant should generally avoid testifying because the prosecution’s cross-examination is often devastating. In this case, however, I would argue that Mr. Chauvin, with a very slim case focused on mildly clouding the issues on cause of death, did not have much to lose. If he had humanized himself to a degree, or if he had simply stood by the assertion that he believed he was following his training, that might have caused one or more jurors to dig in their heels and hang the jury. Of course, we will never know, and it is possible that it could have been even more of a slam-dunk after the prosecution was through with him.

But the fact that then jurors, predictably I’d argue, set aside the instruction to not draw any conclusions from a refusal to testify, is a reminder that jurors are active and often independent decision-makers. They are not passive receptacles for your facts and instructions. Adapt to that.