It comes as no surprise that when a witness is perceived as being credible, his or her messages will be more persuasive to the jury. Much academic research has been conducted to determine the primary characteristics that measure credibility. There has even been a scale developed to measure the perceived credibility of an expert witness via four key factors [1]. For evaluating an expert, the credibility factors are knowledge, confidence, trustworthiness and likability. If any of these four are compromised (e.g., perceived lack of confidence, appears unknowledgeable) then that expert will receive low credibility ratings. The perception of each of these factors is moderated by a variety of verbal, non-verbal and behavioral cues which we review below.

How Do Jurors See the Role of a Retained Expert Witness?

In our 20 years of conducting jury research and participating in trials, we have had the opportunity to interview countless numbers of jurors after actual trials and our mock trials. The feedback we have received between these two venues is virtually the same. Therefore, when we refer to jurors’ feedback, we will be focusing on the totality of comments we have received from jurors. When faced with two competing stories from two parties entangled in a lawsuit, jurors try to simplify the evidence to determine which version of the story makes sense within their own understanding and perception of the world. Thus, jurors will filter the evidence through their personal experiences and attitudes they have formed over the years, as a result of their culture, experiences and upbringing. Not only do jurors filter the case evidence through their sensibilities, they also filter the testimony of the witnesses the same way. When deciding which expert is more persuasive (in addition to the facts outlined below that increase or decrease credibility), jurors filter the expert’s testimony through their own sensibilities. That is, the witness with the message that best aligns with the juror’s attitudes and experiences will have their testimony assimilated into that juror’s version of what happened. Information that is not consistent with their personal sensibilities, is often ignored and not assimilated. Jurors see an expert as someone who clearly and concisely provides information necessary to assist them in evaluating the merits of the case. Neal (2009) tells us, “Expert witnesses are retained to take the stand and share specialized knowledge with the court — specialized knowledge that may help the trier of fact make the decision they are charged to make.” [2] Particularly in a case with a subject area that is foreign and/or complex to jurors (e.g., patents, technical subjects, et cetera), jurors look to the expert to step into the role of professor and succinctly explain the technical concepts in a way they can understand them. When an expert fails at this one specific goal, then his/her testimony is ineffective and lost with the jurors. When we have asked jurors about their view of the plaintiff or defense experts, virtually their first reaction is the fact that the experts were paid for their opinions. In particular, those experts making a high hourly rate or a large flat fee for their time in court are often seen as biased. Most attorneys think since both sides’ experts are paid, it will cancel each other out. However, in most cases, it doesn’t. Instead, in a juror’s ideal trial courtroom, a neutral expert would testify telling the jurors just what happened, making clear who was right and who was wrong. However, as we know, it doesn’t work that way and jurors are left to evaluate the evidence against their own attitudes, experiences and reasoning.

What Do Jurors Consider Important When Evaluating the Credibility of a Retained Expert Witness

The experts who tend to receive high credibility ratings among jurors have several clear qualities that distinguish them from the rest of the pack. Over the years we have tested numerous fact and expert witnesses to learn what factors increase or decrease credibility. For expert witnesses, jurors have provided us a concrete path for the factors that make an expert effective and persuasive. Many of these findings are also supported by the academic research on witness credibility.

    • Experience & Education. An attorney cannot underestimate the importance of on-point experience and advanced degrees for the subject matter at issue. For instance, having an experienced pulmonologist opine on causation for an asbestos or silica case is essential. Or, having an expert who has had the schooling and experience to opine about human factors issues like warnings, helps the messages within their testimony be more believable and therefore, more persuasive.

Not all experts need to have formal advanced degrees that result in numerous initials after their names. We have worked with, and seen on the opposing side, many effective experts who relied on their field experience to bolster their credibility. Jurors like a witness who has either worked his or her way up the professional ladder to be at their prestigious position or who have the hands-on experiences to have first-hand knowledge of the subject matter. Field experience can hold as much or more credibility as a formal degree with jurors, since jurors are in the same situation having to make their own way based on their experiences.

With this in mind, we have seen cross-examination backfire when counsel attacks witnesses who lack a formal advanced degree but have extensive field experience. Field experience can command as much or more credibility as a formal degree with jurors, who tend to view the experience-based expert as similar to themselves. That is, because the majority of jurors do not hold advanced degrees and have years of experience in their jobs, they tend to view a similarly-situated expert in high regard.

  • Personally Engage the Data. Time and time again experts lose credibility because they failed to engage the data, research or even examine a plaintiff. An expert who has not personally engaged the materials and instead relied on research associates to run the analysis and write the report tends to be unsuccessful in persuading the members of the jury. Any witness, not just experts, who are hands on with the data and analysis command more believability. For instance, when evaluating an expert physician who was asked to opine about causation in a personal injury/products liability case, our research has repeatedly shown that jurors value a witness’ testimony less when the doctor only reviews the medical records and never “lays hands on” or examines the Plaintiff (assuming the Plaintiff was still alive at the time the expert was hired). For the physician experts that do, the persuasiveness of their testimony is enhanced.
    So how does an expert counter this criticism? It is important for experts who may not have personally run all the data analyses or completed the literature review, to discuss how they supervised the research process and monitored and approved all work done to their specifications. By providing the appearance that the expert was involved in and supervised the process, that person can then take ownership of the analysis and report and regain the credibility they would have otherwise lost.
  • Source of Information. Another criticism jurors have told us that can adversely affect an expert’s credibility is where the expert used the information received from attorneys as the foundation for their opinions and conclusions. In most cases, experts receive a “file” from the attorneys who have hired them. Similar to the previous issue of not personally engaging or taking ownership of the analysis, jurors are also critical of an expert who only relies on the information that the attorneys provided. Jurors expect that the expert will engage in his/her own level of literature review/research; otherwise, jurors become suspect of the conclusions drawn from such information. When this situation happens (and it happens more than you might think), it reinforces jurors’ belief that not only is the expert’s opinion biased, but it is also being controlled by the attorneys who hired them, thus giving meaning to the phrase “hired gun.”

Now, you may be thinking that it is unavoidable to provide an expert with the litigation file relevant to the case. That is true. However, the factor that affects the witness’ credibility comes in when the expert stops after receiving the attorney’s file. While jurors expect the expert to receive files from the lawyers in the lawsuit, they also expect experts to conduct their own additional work to verify the file is complete and has the most current research to use when developing their opinion. Opinions based solely on the attorney-provided files falls flat among jurors and becomes a strong cross examination topic to explore with experts.

      • Demeanor. Jurors are attuned to a witness’s tone of voice and are critical of witnesses who sound arrogant or condescending. In one example involving a corporate research scientist, jurors noted that his tone of voice and the manner in which he spoke (e.g., proud to discuss his study, provided long-winded answers) made him come across as a “know-it-all,” or stated another way, “He was smarter than everyone else in the room.” As another juror said, “He was so sure of what he knew, he knew more than anyone else.” His “arrogant” and “cocky” demeanor severely undercut any impression he might have made as a knowledgeable witness on the particular subject matter.

As previewed earlier, experts who can channel their inner professor and be able to easily explain complex subjects in accessible, understandable terms, without sounding condescending will be more effective among jurors. Our post-verdict interviews with trial jurors have reinforced the notion that experts who believe credibility is enhanced by spewing technical jargon and complex explanations around the courtroom do not connect with the jurors so they can assimilate the information. Instead, consistent with cognitive psychology as we outlined earlier, information that doesn’t line up with jurors’ sensibility, attitudes or experiences will be cast aside and ignored. Therefore, experts who testify with jargon and complexities are not only confusing the jury but they also are failing in their main purpose – i.e., to clarify and teach the jurors about the subject matter they were asked to discuss. To quote Einstein, “If you can’t explain it simply, you don’t understand it well enough.”

One cautionary note associated with a witness who defaults to using technical jargon is that jurors may perceive him/her as “talking down” to them when the witness tries to simplify his/her message. Sometimes an expert witness “dumbs the message down” to a point that it becomes condescending to the jurors. Therefore, there is a balancing act between being too technical, while at the same time not being too simple or demeaning. As such, experts need to use enough industry jargon to show their experience and knowledge, but also to simplify the technical language enough to be informational in order to establish that jurors can trust the information experts are providing.

      • Balance of Resume. Another level of bias that undermines an expert’s persuasiveness with the jurors is the content of their curriculum vita. Certainly the education and experience play a significant role as discussed above, but it is the expert’s list of cases and who the expert has testified for that can have a different level of impact. It should be no surprise that experts who have been consistently hired exclusively by same side (e.g., only plaintiff or only defense) lack the standing to provide a “neutral” opinion. For instance, if an expert witness has only testified for the plaintiffs, jurors are astute enough to realize his/her opinion is suspect. An expert that can say that, over the years of her career, she has been hired in different cases by either the plaintiff or defendant will exhibit a stronger credibility rating among jurors. Moreover, this effect is heightened when the expert can say she has been approached by the attorneys for one side in a lawsuit and after review of the facts, turned down the offer to be an expert in that case. The benefit here is derived from the fact that jurors believe that if an expert has testified for both sides at any time and/or has turned down others to not compromise their ethics or reputation, then jurors believe she “must really believe in this case.” When a witness appears neutral about who hires him and won’t compromise his reputation for the first one who knocks on his door, his ability to persuade jurors is enhanced.
      • Hourly Rates. While jurors will never be entirely comfortable with the high hourly rates that experts get paid, it is possible to reduce or perhaps even neutralize its impact upon jurors’ credibility assessments. Certainly trying to put the hourly rate into context is one of the more effective ways to counter its influence upon the jurors. That is, when preparing an expert for deposition testimony, one question to ask him is how his hourly fee will be used or allocated. Learning this information may lead to a very helpful answer that will put the hourly wage in perspective. For instance, for most experts, being asked to testify takes them away from their medical practice or their work in the field. To the extent it is truthful, informing the jurors that the money collected will be used to benefit their patients in their clinic (able to do pro bono work), their practice (purchase new state of the art equipment) or their business (helping people in some way) appeals to the altruistic side of jurors. However, if the impression is left with the jurors that the expert is “lining his pockets,” as quoted by jurors, then the expert will appear biased, reinforcing the “paid for hire” stereotype that most jurors hold of experts.
      • Non-verbal and Verbal Characteristics. And of course, the old standbys for evaluating witness credibility apply to experts as well. Many academic research studies have reinforced the findings we have seen in the real world with our actual trial jurors. Characteristics such as good eye contact, avoiding verbose answers, engaging in powerful speech, and appearing likable all impact the way jurors perceive the persuasiveness of the testimony. If experts do not have good eye contact, use powerless speech (i.e., tendency to use language that is perceived as being unsure or lacks confidence, such as excessive politeness, hedges and hesitations, et cetera), the expert will be perceived as lacking in the essential four characteristics that impact and enhance an experts’ credibility – knowledge, confidence, trustworthiness and likability.


Clearly, there are many variables that will affect an expert’s perceived credibility, but, with careful preparation, these variables can be modified in order to strengthen his or her testimony and to ensure it is well-received by the panel. Unfortunately, attorneys have to work against jurors’ preconceived notions about the retained expert’s legitimacy since many believe they are “hired guns” that are paid a hefty hourly rate to give a biased opinion. For this reason, the trial team and expert have an uphill battle to fight from the moment the testimony begins. For the most part, the retained expert will always be walking a fine line between making it clear they have a significant command of the material and not sounding condescending or arrogant. Each one of the factors previously reviewed in this article affects this critical balance. As mentioned, the trial team should be cognizant of the witness’ experience and education and the way it is portrayed to the jurors. An expert does not always have to have an advanced degree to be perceived as legitimate. In fact, oftentimes, real life experience outweighs a formal degree. Additionally, the expert should show the jurors they have personally engaged the data and performed outside research that stretches beyond the documents given to them by the trial team to enhance credibility. Moreover, be aware of the expert’s experience since experts with the most balanced resume will increase jurors’ perceptions of the expert’s neutrality. Finally, make sure that the expert is employing helpful verbal and non-verbal characteristics, such as good eye contact and powerful speech, which will influence the persuasiveness of the testimony. When preparing a witness, the attorney or trial consultant should pay close attention to all of these variables and keep in mind how each influences the expert’s credibility since, in the end, a well-prepared expert is one of the most effective tools in helping you secure a favorable verdict.

  With more than 25 years of experience in the trial consulting field, Dr. Pitera is a psychology and communications expert who specializes in complex litigation and preparing witnesses for depositions, trials and congressional testimony. Merrie Jo is a perceptive listener and observer of witness behavior and provides clear insights into how these verbal and non-verbal behaviors are likely to impact a witness’ credibility with a jury, judge or arbitrator. She is a frequent national and international speaker on jury behavior and witness prep methods. You can reach Dr. Pitera at and can review her witness prep blogs on Litigation Insights’ website:

[1] Brodsky, S.L., Griffin, M.P., &Cramer, R.J. (2010). The Witness Credibility Scale: An Outcome Measure for Expert Witness Research. Behavioral Sciences and the Law, 28, 892-907. [2] Neal, T. (2009, March). Expert Witness Preparation: What Does the Literature Tell Us? The Jury Expert, 44-54