As a party to a court case, how can one motivate to testify a person who has the wanted expertise? Offer them $$$? (Let's not consider those expert witnesses who make living by testifying / actively seek to be engaged. Those are motivated already, but the choice of areas of expertise is very limited)

A typical potential expert witness this question is about may have never been in a courtroom or even engaged a lawyer in their life. When someone approaches them asking "I see you have well-recognised experience in X, would you be interested to be an expert witness in a court case? The question for you would be <specific question about a certain aspect of X>" — they may not even have an idea whether they would or not. They would perhaps like to hear some legal advice about it, but why even bother seeing a lawyer? So, their instinct tells them to just pass as it is totally unknown area to them with unknown risks. Especially if the case they are asked to testify in is a criminal one.

So, how to get those people motivated? How to entice them? How do lawyers do it?

(I have approached about a dozen of Labrador retriever breeders/trainers asking them to testify whether a Labrador retriever would typically chase/attack ducks just by iteself — as opposed to having to be encouraged/commanded to do so. I made it clear that they would be paid and have all expenses covered. Yet only 2-3 of them even bothered to reply, and all those replies were along the lines "not interested", excuses like "I'm not an expert" etc.)

Related: How do lawyers find expert witnesses?

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    Isn’t this a duplicate of the “related” question?
    – sjy
    Commented Aug 6, 2021 at 6:50
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    @sjy No, because in that question the motivation of witnesses is an existing premise. Here it needs to be built from scratch.
    – Greendrake
    Commented Aug 6, 2021 at 6:52
  • What jurisdiction are you asking about? Commented Aug 7, 2021 at 9:36
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    Note that it is very unlikely you will ever find an actual expert willing to testify such a blanket, generalized statement. I certainly hope no "expert" would, at least. The idea that you could make any statement, positive or negative, about whether labrador retrievers, in general, as a breed, would chase a duck seems ludicrous. This is likely making it harder for you to find anyone with actual knowledge being willing to do so. It's basically like asking if a New Zealander would be likely to eat a banana without prompting: some would, some wouldn't.
    – terdon
    Commented Aug 7, 2021 at 16:25
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    @MichaelHarvey Any talks about the actual case are not welcome here. I have provided some info in the question only to give context of where it comes from, and to give an example of what it can be difficult to find expert witnesses for. You are welcome to read about it though, it's just not to be discussed here.
    – Greendrake
    Commented Aug 8, 2021 at 1:05

5 Answers 5


It’s their job

Or, at least, part of their job.

For some, like state-employed medical examiners it’s an explicit part of their job description that they will give expert testimony when required.

For others, it can be something they choose to do as part of their business, either as a side-gig to their “day job” (most experts). Or because their primary business is dispute resolution, this includes many professionals who become arbitrators or expert determiners and offer their services as expert witnesses.

In both cases, it’s a job for which they get paid, and usually, paid handsomely. For example, all the engineering companies that I have been part of charge 3-4x their normal fee for legal work partly because it’s demanding work that distracts from their core business but mostly because of market economics - people will pay more for an expert witness than they will for a consulting engineer even when they’re the same person.

It’s also difficult and nasty work - no one enjoys writing reports that they know are going to be attacked over every inconsistency. As for giving evidence and being cross-examined? Even at $500/h, you’re getting a bargain.

Other people may be motivated by the noble ideal of a just cause. Me? Here’s my bank account, make sure the money’s there before I testify.

So, how much were you offering?

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    Are you saying it's definitely worth offering some figure as opposed to asking what their terms would be?
    – Greendrake
    Commented Aug 6, 2021 at 6:38
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    Possibly. For someone who has never known what this type of work entails, giving them an offer they can’t refuse might be worthwhile. Only you can assess what the right evidence is worth to you.
    – Dale M
    Commented Aug 6, 2021 at 7:05
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    @Greendrake Yes, absolutely. Commented Aug 6, 2021 at 18:23
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    One of my father's oldest friends was an economics Professor, and made serious coin as an expert witness (mostly in civil suits where someone died or was injured, and the plaintiff wanted more than what the insurance company offered).
    – RonJohn
    Commented Aug 7, 2021 at 23:24
  • There are a slue of privately run forensics labs that are available for Criminal Defense Teams to process evidence that will be used against them, as in the U.S. the accused has a right to examine the evidence and thus any lab testing done by the State's crime lab should be duplicable in another lab. These labs are not tax payer funded, and these tests may not be cheap.
    – hszmv
    Commented Aug 9, 2021 at 13:05

The other answers have covered good reasons, but here's one more: when you serve as an expert witness, it demonstrates that at least some people hold you in high regard as an expert on your subject, even high enough regard to pay you handsomely and (to varying extent) stake the outcome of their legal case on your expertise. Having served as an expert witness in a trial is also normally a matter of public record, so it is independently verifiable.

So, people may choose to serve as an expert witness in order to improve their credibility as an expert in their subject area. Being able to say that you have served as an expert witness means you really must be an expert, and that looks good on a resumé or in an advertisement for your consultancy business.

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    I had a grandmother who once testified as an expert witness on quilting in a court case (where the authenticity and merchantability of an Amish quilt was at issue), primarily with that motivation.
    – ohwilleke
    Commented Aug 6, 2021 at 21:03
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    It's not uncommon for engineering consultants to list expert witness experience on their CVs. Commented Aug 7, 2021 at 17:07

Or because they have to.

The other answers are all correct. In practice, @DaleM is "most correct" because the lion's share of expert witnesses either voluntarily agree to do so because they are paid to do so, or because it is part of their job responsibilities (especially people like medical examiners). But @user6726 is not wrong that public spiritedness is sometimes a factor, and @kaya3 is not wrong that improving one's professional reputation is sometimes a factor.

These answer omit the second most common reason that someone testified as an expert, however, which is that they are compelled to do so by subpoena.

Generally, expert witnesses participate voluntarily and are called "retained expert witnesses" who are hired for a particular case. But, sometimes someone who is primarily a party to a case, or is a non-expert fact witness in a case, also has expertise qualifying that person to be an expert witness, if this expected testimony is disclosed when required under court rules.

A typical example would be a treating physician in a personal injury case. The treating physician testifies as a non-expert fact witness (and may be compelled to do so by subpoena) regarding facts about which the physician has personal knowledge such as the fact that the plaintiff in the tort case was treated by the physician (at the scene of the accident on the way to a kid's soccer game, since the physician was passing by) with heavy bleeding from an artery on his right leg and lacerations all over his exposed skin.

But, once the treating physician is on the stand, the physician can also be qualified and examined as an expert witness, whether the physician wants to do so or not, about the physician's expert opinions regarding the matters upon which the physician render lay testimony. For example, the treating physician might be asked: "in your professional opinion was the plaintiff's leg injury the cause of his inability to walk without a cane today?"

Generally speaking, someone compelled to testify as a non-retained expert is still entitled to compensation as if he were a retained expert, at a court determined rate reflecting the expert witness's usual charges for this work, if this is disputed (in contrast, a purely non-expert witness is entitled only to mileage to the court house and a fee roughly sufficient to pay for lunch in amounts set by statute).

Similarly, a party to a case who has pertinent expertise, may and often does testify as a non-retained expert witness, in addition to testifying about the facts of the case (although testimony about the facts of the case is not required for a party-expert), whether or not the party is subject to a subpoena. In this case, the party is not entitled to compensation for testifying (even if called by another party in the case and not in the party's own case). The compensation/motivation is the same as the compensation for testifying as a lay witness (i.e. the ability to provide truthful information to the court to support their case) and the cost for a party-witness is reduced because the party has to be at the trial anyway in some capacity in most cases.


It's not their job

So you need to give them something of value to them. Money might be a motivator. Or, the subject matter might be the motivator. I'm omitting the third category of people with a work-related obligation to testify (government lab workers), which reduces to money ("testify or get fired"). Typically there is a relationship between what a person does for a living and what they are expert in, but the scope of the job obligations usually don't involve serving as a general purpose expert witness.

An example of subject-matter motivation is testimony about language interpretation, such as in a contract or a statute. There is an increased recognition in the US that there is a scientific area of studying language, and expert testimony can inform a judgment as to the possible interpretations of a clause. Experts in this area may be motivated to testify (for a nominal honorarium) as a public service.

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    Testimony as a public service is particularly common in the case of court appointed experts, who may feel an obligation to provide neutral advice to a judge or jury not otherwise available, on behalf of "the system."
    – ohwilleke
    Commented Aug 6, 2021 at 20:59
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    Closely related to truly disinterested public service, is "activism", with a goal to use the knowledge the expert has to advance a cause that is furthered by making courts available of facts related to the witnesses expertise (e.g. a witness testifying about "battered women's syndrome.").
    – ohwilleke
    Commented Aug 6, 2021 at 21:06

I do not consider myself an expert in this field, but I can speak from personal experience.

I've frequently been asked to testify as an expert witness. Each time, money was waved in front of me (not literally, mind you) to testify. Also, almost every time, someone bought me a nice meal during a meeting they set up to ask me.

The only incentive ever offered to me has been financial.

I've turned down 100% of these requests, although I've enjoyed a few nice meals.

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    That makes you one of the type that I have failed to entice then. Why did you not accept any? Was there anything that would have made you accept?
    – Greendrake
    Commented Aug 9, 2021 at 12:18
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    @Greendrake It really depends on why the expert testimony is being requested. When it has been asked of me, it has never been to really help others do anything besides win a case. If I found the case to be ethically powerful, I would certainly consider that to be "helping others", but most of these cases I've been asked to testify in revolve more around money than anything else. As an example, and I'm only basing this on my memory of several articles I read years ago and the movie adaptation, if I was asked to testify for the prosecution in something like... continued... Commented Aug 9, 2021 at 14:27
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    ...the famous Erin Brockovich case (Anderson, et al. v. Pacific Gas & Electric), I would likely not only testify, I would refuse any compensation (or give all my compensation back to the plaintiffs). Commented Aug 9, 2021 at 14:28
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    But I do have a fairly accurate "B.S." meter, and if I think someone is really trying to just pull at my heartstrings more than appropriate for the situation, it would be a big turnoff to ever meet with them again. Commented Aug 9, 2021 at 14:36
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    @Greendrake Someone once tried to convince me to present expert testimony by appealing to what they thought was a universal desire to be powerful. Their mistake was that such a desire is not nearly as universal as they thought. :) It's actually a bit ironic (and sad), but the best expert witnesses for many (but not all) cases are exactly the people who have no interest in being expert witnesses. Sometimes (but certainly not always) the people who wind up being expert witnesses are primarily driven by ego, power, fame, and/or financial gain. Commented Aug 9, 2021 at 14:45

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