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Expert Witness Credibility: What Can Influence Perception?

Cropped view of two doctors woman and man in medical apparel holding x-ray rib cage, lungs, thorax

Expert witnesses are judged on several criteria, fairly or unfairly. Their success in the courtroom depends on many factors that, combined, affect whether the jury finds the expert credible and their opinion persuasive. Read on for a discussion of what makes an expert witness credible and successful, and call an effective medical expert witness with any additional questions.

Education and Experience

An expert’s qualifications are used for more than convincing a judge to admit their opinions. An expert’s education and relevant experience in the field will help convince the jury that the expert should be taken seriously. A witness who went to an unknown school and has limited real-world experience might not be especially persuasive. A witness with an impressive resume, who attended a reputable school, and with years of experience and professional publications will strike as much more credible to the jury.

Perceived Bias

No one likes a liar. Anything that might be used to undermine the trustworthiness of an expert witness can do serious damage to their credibility with the jury. An expert who has testified on both sides of the same issue may be seen as loyal to whoever pays them. An expert who always testifies on the same side of disputes (such as a medical expert who only testifies for the defense in malpractice suits) might be seen as biased in favor of one side, causing the jury to discount their opinion. Personal connections to the matter at bar can also affect their credibility. When retaining an expert witness for your case, make sure that you are fully aware of any factors which could imply bias, and be sure to either address those issues in your preparation or find a new expert.

Poor vs. Effective Communication

Being smart, educated, and experienced in the relevant field does not necessarily mean an expert witness will be effective. An expert witness has multiple goals when providing testimony:

  • Explain complicated or technical concepts to the jury
  • Educate the jury about technical concepts or hard-to-grasp pieces of evidence
  • Explain how the evidence supports their opinion regarding the case
  • Convince the jury that their opinion is the correct interpretation of the facts, the evidence, and the scientific or technical concepts at play

If an expert witness is unable to explain complicated concepts in layman’s terms, a jury might simply be left unable to understand their testimony. Likewise, if the expert keeps getting stuck on unrelated or unimportant tangents about their field of expertise, a jury will have difficulty separating out what actually matters to the case and may simply get bored. A jury that feels confused or lost is unlikely to find an expert’s opinion persuasive. Moreover, the expert must explain these concepts without condescending to or otherwise alienating the jury.

An expert witness must be well-spoken and clear, focused on the facts and opinions that matter for the case, and speak to the jury in a language they understand. The jury must be taught the facts and the expert’s opinions without leaving them bored, agitated or confused. Effective communication is key to persuasive expert testimony.


How an expert witness stands up to cross-examination can make or break their testimony. If opposing counsel is able to trip up the expert by pointing to contradictory statements by the expert, holes in their expert opinion, or evidence that undermines the expert’s argument, a jury may be swayed into believing either that the expert does not know what they are talking about or that they are flat-out lying.

Experts must know their opinions inside and out in order to withstand cross, and they should have a firm grasp of all facts in the case that relate to their opinion and could be used to bolster or undermine their claims. Experts must also be able to address and explain away any contradictions in the evidence or their own prior testimony–if opposing counsel brings up an opinion the expert provided or a paper they published years back that directly contradicts their current arguments, the witness might look biased or unprofessional.

If you need a qualified, thorough, and successful expert witness in a personal injury, medical malpractice, or product liability case, contact the offices of Neurosurgery Medlegal Services, LLC, at 866-659-8051.

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