What Makes Your Expert Witness the Best Witness? Social Science Research on Credibility and Influence Points the Way

What Makes Your Expert Witness the Best Witness? Social Science Research on Credibility and Influence Points the Way

Expert WitnessThe adversarial nature of a jury trial leads many of our clients to ask: “Will my expert come across better than theirs?” This is a justifiable concern, since jurors’ decisions about liability and damages often hinge almost entirely on the testimony and credibility of the expert witnesses.

Evaluating a potential expert based on credentials and experience is only half the analysis. Particularly when an expert is addressing a complex subject, jurors may have difficulty understanding the technicalities associated with their explanation and rely instead on heuristics—like credibility—for evaluating the testimony.[1] In other words, the jurors rely on their opinion of the expert rather than the expert’s opinion. As a result, attorneys must attend to the expert’s projected credibility in addition to the content of their testimony.

Credibility is the foundational element that enables experts to successfully persuade jurors, and it has been the subject of social scientific research for decades.[2] Through the combined efforts of The Focal Point and IMS ExpertServices, we are able to offer our clients the best possible experts for any given case. This article discusses some of the social science research on credibility that informs our recommendations and training methods. 


Knowledge is the primary reason experts are called to testify: their expertise is supposed to be beyond question and ensures that their testimony informs the jurors. The domain of knowledge coalesces educational credentials, publications, and experience, each of which make an expert look great on paper.[3] But knowledge is also a product of clarity in explanations, moderate assertiveness, and familiarity with the intricacies of the case.[4] These latter factors serve to distinguish a good expert from a great one. Addressing each of these items during witness selection and preparation is critical to the success of a case presentation.  

Experts may look great on paper yet fail in front of the jury. An expert may be the preeminent expert in a given field, but if they cannot clearly explain the concepts to the jury, their persuasive power is lost. When an expert folds on cross-examination and fails to assert counterpoints, the jurors often believe the opposing counselors have “beaten” the expert and discount his testimony.

Not all experts take the time to ensure they can convey their knowledge. Some experts will fail to personally learn the case, and they may hand the work off to an associate. Either at deposition or at trial, these experts lose credibility when they cannot command the facts in a way that coincides with attorneys’ case analyses.

The best way for expert witnesses to showcase the extent of their qualified knowledge is to act as teachers for the jury: they should be consistent and coherent as they enlighten the jurors on a concept, they should demonstrate reasonable confidence in their own conclusions and opinions, and exhibit case-specific knowledge to complement their topical knowledge.[5]


Trustworthiness is a characteristic that is crucial to jurors’ decisions as to whether to believe or dismiss expert testimony. While jurors may recognize that experts are inherently biased—after all, each expert appears as either a “defense witness” or a “plaintiff witness” rather than a “neutral witness”—the extent to which jurors trust their testimony is tied to a number of factors.

For one, the above described perception of expertise is likely associated with perceived trustworthiness, as these factors tend to be quite interrelated.[6] An expert who embodies a patient and considerate teacher is likely to be perceived as quite trustworthy.

Second, an expert’s demeanor on the stand influences jurors’ evaluation of her trustworthiness. There are nonverbal cues that are traditionally thought to be indicative of honesty or dishonesty. For example, one study found that an expert witness’ ability to maintain eye contact with both the attorneys and jurors was predictive of credibility ratings.[7]

Third, empirical research has shown that the number of times an expert has testified and their compensation are both associated with perceptions of believability—also known as the “hired gun effect.”[8] Often this effect arises when there is a huge disparity between the amounts opposing experts are compensated. For instance, jurors may be suspicious of an expert in an antitrust case who receives $300,000, while the opposing expert is paid $30,000. To combat jurors’ perceptions that a higher paid witness is simply a hired gun, the witness’s testimony must assure jurors that payment is merited due to the witness’s exceptional level of expertise.   


The ability of a witness to exude charisma and dynamism is hugely important. Many experts are asked to expound upon complex and arcane concepts which are difficult for juror laypersons to comprehend. In these instances, jurors rely on heuristic cues like credibility to guide their evaluation of the testimony.[9] An expert witness may endear themselves to a jury by using simple terms or metaphors, by integrating demonstratives, and by remaining patient and steadfast during cross examination.[10]

An effective expert is not merely perceived as a trustworthy intellect, but as someone who is considerate enough to take the time to convey their knowledge in ways the audience can understand. An expert’s dynamism, coupled with display of their deep passion for and mastery of the subject matter, will frequently carry the day.


Finally, there is the rather broad question of whether an expert is likable. It is indeed rare that a knowledgeable, trustworthy, and dynamic witness will be unlikable, but most lawyers have encountered at least one arrogant or rude expert. Likability has been found to be tied to both perceptions of trustworthiness and credibility as a whole.[11]

Many attorneys have experienced a sinking feeling while watching jurors react negatively to an expert who offers a sarcastic response during cross examination. The expert witness who is disliked by a jury will torpedo their own testimony: while jurors might believe the expert is very competent and knowledgable, they may dismiss the testimony on the basis of their dislike for the expert. Worse still, they may channel this dislike to the party that the expert represents. Jurors assess the likability of witnesses based upon their friendliness; the level of respect they show to the parties, the jury, and the court; their ability to use informal language, and the various nonverbal behaviors they exhibit, like eye contact and vocal inflection.[12]

Our Services

We welcome attorneys to take advantage of the combined experience and talents The Focal Point and IMS ExpertServices offer to enable experts to testify successfully. Not only will our IMS client managers find the most credentialed and experienced experts in a given domain for a case, but our TFP consultants can help those experts demonstrate their knowledge in ways that appeal to jurors. Furthermore, we can develop graphics and vivid presentations to be used as teaching tools to highlight witnesses’ topical expertise and aid their explanations.

We help experts convey their knowledge. We ensure they comprehend the attorneys’ case analyses so that their testimony is compelling for jurors. We help expert witnesses become teachers so they can clearly convey complex topics to a jury.

In terms of trustworthiness, expert witnesses can be prepped to mitigate the hired gun effect and the impact from their inherent bias as a plaintiff or defense witness. We help elicit testimony that enables witnesses to convey the hours they spent on the case and how their compensation is related to their careful study of the facts. We place a particular focus on nonverbal behaviors that jurors may view as signs of dishonesty. We ensure witnesses present a consistent demeanor throughout the deposition and trial process, since jurors tend to negatively assess behavioral differences experts exhibit between the various stages of testimony.

We help experts become dynamic presenters who are able to sway jurors. They become able to convey material using analogies and images. We develop graphics for them so that they testify powerfully, vividly, and persuasively.

Making an expert witness likable can occasionally be a challenge. Their expertise may predispose them to testifying with arrogance, and if they fail to acknowledge reasonable uncertainty in their findings or act respectfully toward all of those involved in the trial, jurors may question their trustworthiness. We help ensure an expert witness remains likeable throughout the presentation by coaching them to appear sincere and humble. It can be tough for attorneys to preserve a quality working relationship with experts by candidly challenging their likability. Utilizing a consultant allows for a third-party to have the difficult conversations and challenge the expert to be better without spoiling this relationship.

In summary, attorneys already understand the import of expert witnesses for their cases, and both IMS and The Focal Point offer services to maximize the opportunity an expert presents. Expert witnesses often prove to be the lynchpin of a case, and our expert searches combined with our consulting ensure that this cornerstone exceeds expectations.

[1] Chaiken, S., and D. Maheswaran. "Heuristic processing can bias systematic processing: effects of source credibility, argument ambiguity, and task importance on attitude judgment." Journal of Personality and Social Psychology 66, no. 3 (1994): 460.

[2] McCroskey, J.C., and T. J. Young. "Ethos and credibility: The construct and its measurement after three decades." Communication Studies 32, no. 1 (1981): 24-34.

[3] Cooper, J., E.A. Bennett, and H.L. Sukel. "Complex scientific testimony: How do jurors make decisions?." Law and Human Behavior 20, no. 4 (1996): 379-394.

[4] Neal, T.M., R.E. Guadagno, C. A. Eno, and S. L. Brodsky. "Warmth and competence on the witness stand: Implications for the credibility of male and female expert witnesses." Journal of the American Academy of Psychiatry and the Law Online 40, no. 4 (2012): 488-497

[5] Brodsky, S.L., M. P. Griffin, and R.J. Cramer. "The Witness Credibility Scale: An outcome measure for expert witness research." Behavioral Sciences & the Law 28, no. 6 (2010): 892-907.

[6] See note 2 above.

[7] Neal, T. M., and S. L. Brodsky. "Expert witness credibility as a function of eye contact behavior and gender." Criminal Justice and Behavior 35, no. 12 (2008): 1515-1526.

[8] Cooper, J., and I.M. Neuhaus. "The “hired gun” effect: Assessing the effect of pay, frequency of testifying, and credentials on the perception of expert testimony." Law and Human Behavior 24, no. 2 (2000): 149-171.

[9] See notes 1 and 3 above.

[10] Ivković, S. K., and V.P. Hans. "Jurors' evaluations of expert testimony: Judging the messenger and the message." Law & Social Inquiry 28, no. 2 (2003): 441-482.

[11] Brodsky, S.L., T.M Neal, R.J. Cramer, and M.H. Ziemke. "Credibility in the courtroom: How likeable should an expert witness be?." Journal of the American Academy of Psychiatry and the Law Online 37, no. 4 (2009): 525-532.

[12] Beebe, Steven A. "Effects of Eye Contact, Posture and Vocal Inflection upon Credibility and Comprehension." Educational Resources Information Center. (1976).


What Makes Your Expert Witness the Best Witness? Social Science Research on Credibility and Influence Points the Way

Appeared in IMS | TFP Insights

July 08, 2020


Clint Townson, Ph.D.

Clint Townson’s background in the fields of communication and trial consulting prepared him well for his position as Jury Consultant at IMS | The Focal Point. As an expert in the field of communication, he knows how to deliver crisp, effective courtroom messages.

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