How Jurors Respond to Expert Witness Confidence and Why Attorneys Should Prep Their Witnesses

Defense Attorney: Doctor, how confident are you in your opinion that Mr. Smith is incompetent to stand trial?

Expert: I am 99% confident.

Defense Attorney: No further questions, your honor.

Prosecuting Attorney: Doctor, can you tell me the competency statute on which you based your opinion?

Expert: Excuse me?

Prosecuting Attorney: I would like to know what aspects of competency you evaluated and if they match with the legal definition.

Expert: Well, I don’t know the statute off the top of my head. I don’t memorize the laws.

Prosecuting Attorney: What aspects of competency did you evaluate then"?

Expert: I’m not sure how that’s relevant… I did an evaluation …um … … could you repeat the question?

I paraphrased this exchange from a contested competency hearing I witnessed about ten years ago. The psychologist, who had been qualified as an expert, testified that he was convinced the defendant was incompetent and his level of confidence in his opinion was near 100%. As with most people who think they are 100% correct, he came across as smug and condescending on the stand. When the prosecuting attorney questioned his methods and conclusions during cross examination, the expert was appalled and accused the attorney of acting unprofessionally. At this point, my jaw was on the floor as it dawned on me that he didn’t understand the adversarial nature of the court system and had no idea someone might think that maybe he was wrong.

Not surprisingly, the judge ruled the defendant was competent to proceed with adjudication, and I received a nasty email from the expert the following week accusing me of violating several sections of the American Psychological Association’s ethics code (because I helped the attorney develop cross examination questions).

This anecdote is a long-winded way of saying that expert witness confidence is a complicated construct. Research clearly shows that jurors pay attention to the level of confidence expressed by experts on the stand. But, they also have fairly decent BS detectors. In fact, a study from 2009 determined that moderate levels of confidence increased the expert’s believability in the eyes of jurors. Too little confidence: jurors saw those experts as inexperienced and unknowledgeable. Too much confidence: jurors were annoyed, although they still found these experts as more believable than those who had little confidence in their opinions.

The 2009 study found that expert witnesses who expressed a moderate level of confidence on the stand stood out from their self-deprecating or narcissistic peers: Jurors found them more likable, more trustworthy, and more knowledgeable.

At this point, let me also say it is important for expert witnesses to actually be knowledgeable and credible. They need to have conducted a thorough, unbiased evaluation of the available data and have come to objective conclusions that take into account evidence that does not corroborate their opinions. Only after that should an expert try to come across as moderately confident—anything else is just trickery and blatant jury manipulation.

And a further point: there are two factors that moderate whether or not jurors find expert witnesses believable. First, extraverted jurors tend to find all experts as more believable than introverted jurors. And second, when attorneys prepare their expert witnesses prior to testimony, those experts end up being rated as more confident.

One more thing, and this may be the key: Jurors in the 2009 study reported the credibility of the experts in the case weighed heavily in their minds when they decided on sentencing. Expert credibility can actually predict jury outcome!

If the woefully unprepared psychologist from the beginning of this post had been prepared by the defense attorney, he might have been less arrogant on the stand and less shocked during cross examination. Of course, the defense attorney might have also discovered ahead of time that the psychologist had not conducted a proper evaluation and did not know what he was talking about in the area of adjudicative competency. That would have given the defense attorney the opportunity to find a new psychologist who was qualified or to stipulate competence without a lengthy hearing (this particular hearing took roughly 8 hours of court time, spread out over several months; I’m not kidding—this competency hearing took months).

Imagine if a situation like this had happened in a civil case and an attorney just accidentally spent tens of thousands of dollars of his/her client’s money while simultaneously jeopardizing a sizable jury award.

The moral of this story? Attorneys: Find credible experts and then prepare them for testimony! It may be more expensive in the short-term, but it will pay off for your client in the end.

reference: Cramer, R. J., et al. (2009). Expert Witness Confidence and Juror Personality: Their Impact on Credibility and Persuasion in the Courtroom. The Journal of the American Academy of Psychiatry and the Law, 37(1), 63-74.