Unless you're in some public office (in which case you are compelled to), expert witnesses are monetarily compensated "handsomely" to offer their testimony. See https://law.stackexchange.com/a/70502/45435

But isn't this a clear conflict of interest? If I was told for some Amazon review "We paid this guy thousands of dollars, and he just happened to review us 5 stars ^_^", how is anyone supposed to believe that? Similarly, in a court, the exact same thing is happening, right? E.g. "We paid this expert engineer thousands of dollars, but he says it's a random error that could've happened, okay? ^_^".

Or is the fact that expert witnesses get huge payments just completely swept under the rug and out of sight of jury consideration? Similar to how jury nullification isn't explicitly instructed to jurors because it would only complicate the process?


4 Answers 4



Experts’ time is valuable. Courts would not be able to get qualified experts to testify if they were not compensated. As per your previous question, the crucial point is that they are paid to tell the truth, not to be an advocate for one side.

But Sometimes Yes

There have been scandals where a cottage industry of experts sprung up, based solely on there being a market for expert witnesses. These witnesses knew that the way to keep getting hired was to always confidently testify that they could prove the defendant’s guilt beyond a reasonable doubt.

Bite-mark analysis is an entire field which is now held to have operated as a pseudoscience, and where some prolific “expert witnesses” were caught committing fraud.

Similarly, the Texas Forensic Science Commission conducted a review of numerous wrongful convictions for arson in 2012, although there the motive was not money. They were not being paid to testify one way and not the other. Forensic examiners in Texas were simply basing their testimony on myths and old wives’ tales handed down by their predecessors, which turned out to be false when tested under the scientific method. When put to the test, accidental fires could cause all the signs that Texas forensic examiners had sworn were proof of the use of an accelerant to commit arson. Again, though, these “experts” got their jobs by always giving the prosecution the evidence of guilt it wanted.

I have listed examples of experts shilling for the prosecution, mainly because most of the cases that come to mind of highly-compensated experts shilling in defense of someone work for corporations on what are more political than legal controversies.

Even Then, not Really

Even in those examples of misconduct (or incompetence), the false experts were caught because the defense was allowed to hire experts of their own. If the only experts allowed to testify had been the state’s forensic examiners, no one would ever have tested their claims about the difference between arson and accidental fires scientifically. Even though they had no direct financial incentive to testify, they saw their jobs working for the state as working for the prosecution.

Removing the financial motive would not remove all possible bias or suspicion of bias, either. For example, in the wrongful-conviction reviews of both bite marks and arson, one of the most common counterarguments were that the experts arguing to overturn the convictions of people who had no money to pay them were passionate opponents of the death penalty, and therefore supposedly biased.

  • Precisely. Which is why my question stands: why is this at all considered decent practice? Sure, the person paid $10k by a company could be giving a legit review, but there's every reason to believe otherwise. At least in computer sercurity (where I have a background), "blind optimism" is not grounds for anything. If it can be exploited easily, there's every reason it should be and will be. The only contradiction I can find is that the Jury is kept in the dark, similar to Jury nullification, just because it would complicate and throw a wrench in matters.
    – chausies
    Jun 12, 2022 at 4:40
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    @chausies The way it’s supposed to work is that the experts are actual experts whose claims can be scientifically tested, and who care about their professional reputations. In both of the cases I mentioned, genuine experts eventually debunked the pseudoscience. This is, in fact, one important reason we allow the defense to hire its own experts to rebut the prosecution’s.
    – Davislor
    Jun 12, 2022 at 4:45
  • Thank you. That's about what I thought. It's just that, "fact" is rarely ever the case. Psychological evaluation, or even hard-core STEM sciences aren't comprised of monolithic "fact". They all have experts who argue on opposite sides. A random man on the street can tell you the "fact" that my client has a bullet in their head. But I can find 10 experts to argue both sides of whether that bullet in his head was fatal or salvageable. So all I want to say is, since "expert testimony" is clearly not cut-and-dry fact, the money involved in soliciting their opinion must be a problem, ya?
    – chausies
    Jun 12, 2022 at 5:37
  • @chausies This isn’t really a great place for that kind of back-and-forth debate. I tried to write an informative answer, but I can’t tell you how the system ought to work.
    – Davislor
    Jun 12, 2022 at 5:56
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    @chausies Give them no money, and all you have is some random dude from the street with time on their hands and people with an ax to grind. While monetary incentives may create an avenue for corruption that works against justice, ultimately greater interests of justice are served and created by giving compensation to bring forth those who can provide the court with useful, non-trivial information about the facts. All things are a balance, you can't expect anything to work if you require it to be 100% problem free. Jun 12, 2022 at 7:51

Or is the fact that expert witnesses get huge payments just completely swept under the rug and out of sight of jury consideration?

From personal experience as a juror, it is up to the trial lawyers if expert witness compensation is on the record. The last trial I was a juror on had dueling expert witnesses. The prosecution's expert was from the county crime lab. On cross-examination, the defense attorney asked them if and how much they was being paid for their testimony. The prosecutor objected, but was overruled so the witness replied that their testimony was part of their job and told us their annual salary (which is public record anyway). When the prosecutor cross-examined the defense's expert witness they asked the same question, and the expert witness quoted their rates. During jury deliberations we all found the questions amusing (and a little annoying) because we all knew that the experts were being paid to testify. The fact that both expert witnesses were being compensated had (to the best of my knowledge) no bearing on their credibility or on the resulting verdict.


Yes, but so what?

Most (all?) common law countries follow an adversarial system, where the court is a referee. Parties run their pre-trial investigation and choose their witnesses with a relatively large degree of autonomy. As such, an expert witness is clearly identified as the witness that one of the sides decided to call. The other side will have an opportunity for cross-examination, to point flaws in their testimony or cast doubt on the expert’s credibility.

Davislor’s answer describes criminal trials. In such instances, one party (the state or federal government) has essentially unlimited resources but bears the burden of proof. By contrast, the defendant usually does not have the resources to put up an opposing expert, but might still decide to try to go to trial for a host of reasons. In that situation, the local "expert witness industry" in topics related to criminal cases is hired disproportionately by the state/feds.

Compare to civil cases. Going to trial in a civil case is an expensive proposition, but even more so when one has to pay experts. Therefore, in the fraction of cases that go to trial, the plaintiff expects that the defendant can pay a large award. In turn, that means the defendant can afford to call expert witnesses of their own.

An extreme example would be Oracle vs. Google, where Google put up an expert witness for matters that could clearly have been explained by some of their internal staff. Presumably, this was done to impress the jury with an "impartial" witness.

Of course, that approach to expert testimony is considered unfair by some. Detractors of the "battle of experts" say that the system favors rich parties who can pay famous experts which will impress the judge/jury, even though the opposing party’s expert might have the better side of the scientific debate. That criticism overlaps with the more general criticism that common-law/adversarial systems are alledgedly more biased towards the rich parties than civil-law/inquisitorial systems.

Another approach: civil law

France is a civil-law system with an inquisitorial system. For criminal cases, the judge(s) is (are) running the show. Experts are called from a local list maintained by the court, and paid by the courts (rather than either party).

The risk of bias in such a scheme is fairly low, because the expert is not compensated by either party. However, courts are notoriously underfunded and experts are paid late and not much, which certainly does not attract the best talent. Another problem is that expert testimony becomes much harder to challenge, as hiring a "counter-expert" is not feasible.

While (to my knowledge) bite-mark analysis never made it into French courts, another pseudoscience did. Psychoanalysis (the Freudian stuff) is by and large considered a pseudoscience by psychiatrists/psychologists. However, many court experts are psychoanalysts, who make it to the expert list thanks to a psychology degree, but use the Freudian (pseudoscientific) analysis when performing their services. There is no Daubert motion to be done to exclude such expert testimony, and that testimony is often written (the French procedure does not require all witnesses to testify orally), so there is not much a party can do to contest it (lawyer: "it’s pseudoscience!" judge: "from our court expert? I don’t think so"). There is an ongoing debate to purge those from the expert list (link in French to an advocacy piece).

The interested reader might want to consult Comparative Study on Expert Witnesses in Court Proceedings, a freely-accessible 2009 report commissioned by the Turkish judiciary, which compares the status of experts across France, Germany, Italy, and the United States in much detail (I only skimmed the executive summary).



Experts work for the court. Just like the judge. And the lawyers.

All but one of these is paid by the parties directly. Of course, in an arbitration, the arbitrator is paid by the parties.

Furthermore, the expert is an officer of the court; their loyalty is to the court, not to the party that pays them. As such, an expert that crosses into advocacy will have strips torn off them and be very clearly reminded what their roll is: seen it happen, done it myself.

From the Uniform Civil Procedure Rules Code of Practice for Experts:

An expert witness is not an advocate for a party and has a paramount duty, overriding any duty to the party to the proceedings or other person retaining the expert witness, to assist the court impartially on matters relevant to the area of expertise of the witness.

  • 2
    How is the expert an officer of the court?
    – bdb484
    Jun 12, 2022 at 5:40
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    @bdb484 There are "court experts" which is a special class of expert witnesses. More in this question. Not what the OP is asking about though.
    – Greendrake
    Jun 12, 2022 at 6:48
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    All expert witnesses' primary duty is to the court indeed. But calling them all (except for actual court experts) "officers of the court" is a stretch. This is unlike lawyers who are indeed officers of the court.
    – Greendrake
    Jun 12, 2022 at 7:04
  • @Greendrake they are exactly like officers of the court
    – Dale M
    Jun 12, 2022 at 8:33

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