Opinion: The truth about jurors and body language

James Chalmers and Fiona Leverick respond to recent articles on assessing the credibility of jurors in criminal trials.

Our recent study of how jurors assess credibility in criminal trials has received some attention in Scottish legal news. In this study, we reported the findings of a large-scale mock jury study regarding the cues jurors use to assess the credibility of witnesses. We found plenty of evidence of good practice in this regard. We also found an inappropriate reliance on the body language of witnesses to draw conclusions about their sincerity.

As of August 31, 2022 SLN article Juries should be told to ignore body language, say academicsThomas Ross QC claimed that “the conduct of mock jurors in a small sample of mock trials is used as an argument to abolish [jury trial]and replace it “with the test system in North Korea and Saudi Arabia”. (We did not argue for non-jury trials, only to rethink a line in the standard directions currently given to juries.) The next day at Mock trials are no substitute for reality, Douglas Cusine wrote that “in the latest research on body language, it is suggested, rather oddly in my opinion, that jurors should be instructed to ignore body language”. (In fact, our article suggested that asking jurors to ignore body language would be unnecessary and possibly even harmful.)

Our research is, in fact, based on test simulations. These provide valuable evidence on how jurors in real trials would assess the credibility of witnesses. Mr Ross suggests that our jurors were more likely to rely on body language because they knew that if an actor was “fiddling or licking their lips, because there was absolutely nothing for an actor to nervous, then presumably mock jurors could easily overlook nerves as an explanation.” But that wasn’t true – in 27 of the 64 trials, jurors relied on witnesses’ “nervousness” to assess their credibility. There is no magic wand that suddenly changes the beliefs of jury-eligible audience members (like our jurors were) when they walk into a real jury room. Jury Manual recommends Scottish jurors be told they can look at body language to assess credibility, so it’s no surprise our jurors have done so. They conscientiously followed the instructions given to them.

We suspect we won’t be able to persuade Mr. Ross or Mr. Cusine that the mock jury search is valid. But even if we don’t, we’d like to correct the record of our recommendations. Our rather moderate suggestion in the paper is that “we should certainly not specifically order jurors – as judges in Scottish courts currently do – to pay attention to factors such as body language when assessing credibility witnesses”. Nowhere do we suggest that jurors be directed to ignore it. In fact, we said that “simply asking jurors to ignore behavioral cues is unlikely to be productive (and may even perversely turn their attention more toward them)”. And U.S certainly we are not suggesting in the document that juries be abolished. What we suggest (again, we thought without controversy) is that jurors could benefit from more help in understanding what factors are useful in assessing credibility.

And the idea that body language is a good indication of truthfulness is a false belief. Eye contact (or lack thereof), fidgeting, hand movements and other bodily “tics” are not specific ways to assess credibility, as demonstrated by the wide range of research we describe in the paper. Ignoring these false beliefs risks inaccurate trial results, whether acquitting the factually guilty or convicting the factually innocent. We are sure that Mr. Ross and Mr. Cusine will agree that this is not a desirable outcome.

James Chalmers and Fiona Leverick are professors at the University of Glasgow. Their co-author, Vanessa Munro, is on vacation. After reading recent articles, they wish they were too.

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