By James J. Mangraviti, Jr. Esq.

I have had the honor and pleasure of teaching, training, and preparing expert witnesses since 1996.  Over the years, I have seen expert witnesses repeatedly make the same mistakes when providing their expert witness testimony.  These mistakes when providing expert witness testimony are typically 100% avoidable.  The three most common expert witness testimony mistakes I see are:

  1. Providing expert witness testimony outside of the expert’s true area of expertise and comfort zone. When an expert offers expert witness testimony outside of their true area of expertise they are needlessly putting their reputations at risk.  Offering expert testimony outside of the expert’s true area of expertise often comes about because the retaining lawyer has requested such an opinion. This may occur because the retaining counsel does not recognize the limits of the expert’s qualifications or because the lawyer is looking to save money by not having to hire multiple experts.  A wise expert witness will firmly and politely refuse to provide expert witness testimony in areas that are not fully within their area of expertise.   

Example: An emergency medicine physician is consulted in a case against an ER doctor who treated an accident victim who sustained a closed head injury with internal bleeding.  The ER doctor expert witness is asked to opine on whether the defendant doctor breached the standard of care by failing to order a CT scan that would have detected the bleed and whether said failure caused the plaintiff harm.  In a situation like this the ER doctor expert witness would likely NOT be qualified to address the issue of causation.  Typically for causation a neurosurgeon who be needed to provide the expert witness testimony that had the bleed been detected earlier it would have more likely than not been treatable.  An ER physician is typically not qualified to provide this causation opinion as ER doctors do not perform brain surgery to treat internal head bleeds.  The ER doctor in a situation like this should inform his/her retaining counsel that he/she can only provide an opinion on standard of care and that the attorney will need to hire an expert witness in neurosurgery to address the issue of causation.

  1. Providing expert witness testimony without doing one’s homework. According to Federal Rule of Evidence 702, expert witness testimony must be based on “sufficient facts.”  An expert witness who has not done their homework can, and often is, easing pickings during cross examination (or as we at SEAK would say, “fish in a barrel”).  To avoid making this common mistake expert witnesses should not offer expert witness testimony and opinions unless they have all the information they need to form a solid and reliable opinion.

Example:  We worked with an engineering expert in a case where the expert witness was asked to opine on what caused damage to a roof.  For various reasons (including a tight time deadline and inclement weather) the expert witness never examined the roof in question.  This expert witness testimony was challenged and a motion was made by the opposing lawyers to throw the expert in question off the case.  The case settled before the motion was ruled upon.  Had the case not settled, the expert, in my opinion would have been excluded by the judge for essentially not doing his homework.

  1. Not listening actively and carefully to the actual question being asked. Success at delivering expert witness testimony is often more about listening than speaking.  An expert witness can not excel when providing testimony unless they are superb listeners.  Many experts, especially new ones, are poor or mediocre listeners.  This can be because experts are not used to in their everyday lives being interrogated and asked questions that are by nature designed to trick and trap.  It is also caused by nerves.  To avoid making this mistake experts should focus on listening carefully to the question, repeat the question back to themselves silently, and try to picture the question in their mind as if it were written out on a white board.  Every word in the question should be listened to and focused on. Nothing should be assumed. The expert should answer the actual question he/she was asked, not the questions he/she thought she was asked or should have been asked.

Example.  An expert is asked at deposition or trial “How much are you being paid for your testimony here today?”  Most novice experts will only hear “how much” and “paid” and will answer with their hourly rate.  An expert who is skilled and trained in providing expert witness testimony will instead focus on EVERY WORD in the question.  The key to this trick question is “for your testimony.”  Once the active listener recognizes this, the response is easy, “I am not being paid for my testimony, I am being paid for my time.”

Conclusion:  Expert witness testimony can be delivered at a much higher level when experts recognize and avoid the mistakes commonly made when testifying as an expert.  Undergoing training in testifying as an expert witness can help greatly in the delivery of expert witness testimony.

James J. Mangraviti, Jr., Esq., has trained thousands of expert witnesses through seminars, conferences, corporate training, training for professional societies, and training for governmental agencies including the FBI, SEC, IRS, NYPD, Secret Service, and Department of Defense.  He is a former litigator with experience in defense and plaintiff personal injury law and insurance law who currently serves as Principal of the expert witness training company SEAK, Inc. Mr. Mangraviti received his BA degree in mathematics summa cum laude from Boston College and his JD degree cum laude from Boston College Law School.  He is the co-author of 31 books, including: How to Write and Expert Witness Report; How to Be a Successful Expert Witness: SEAK’s A-Z Guide to Expert Witnessing, How to Be an Effective Expert Witness at Deposition and Trial: The SEAK Guide to Testifying as an Expert Witness. Mr. Mangraviti was the co-founder in 2000 of SEAK’s Expert Witness Directory . Mr. Mangraviti has designed dozens of expert witness training programs and has personally taught experts in a group setting over 200 times since 1997. He can be reached at 978-276-1234 or