Every Economist who is consistent with their discipline subscribes to the subjective theory of value; how does a Judge who wants to be consistent with Economics and coincidentally also is a B.A in economics deal with an Expert Report that treats Value as Objective?

Law frequently deals with value (the value of something; at what price it would be bought or sold) but seems to take lightly the philosophical depth of the concept of Value. It seems that a judge should accept the expert opinion as is and can't consider its methodology or philosophy. We just let the expert tell us what value is without any thought. It is what it is.

Above was the previous phrasing of the question. A more general phrasing would be

How can a judge deal with methodological flaws in expert opinions?

The above is an example when the expert says the Value of X item is Y but it can't actually be bought or sold at that price. The Judge may have personal expertise in the field of the expert opinion or it can be common knowledge. Do we just say expert opinions are what they are and we must accept at face value the least fallacious?

I am asking in the Context of how courts in Civil Law system appoint Experts.

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    Which jurisdiction are we talking? In some jurisdictions, judges can't determine the value of things but rely on a court-appointed expert, in others they have to assume the listed value of things, in others they have prescribed formulas - this all depends on the rules of the court.
    – Trish
    Jan 24, 2022 at 19:54
  • @Trish It is a question precisely on Jurisprudence/Philosophy of Law. It is not about some specific jurisdiction (but since I was taking about expert opinions It is safe to assume that the question was talking about the jurisdiction that have their judges "rely" on court-appointment experts). It is about the treatment of concepts outside of the Law (in particular Value). Jan 24, 2022 at 20:32
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    Jurisprudence in which legal system? What is good in one system is not in another. Just look at the difference between how the value of a stolen good is determined in Germany (market value of a similar product) from the Code of Hammurabi, where the value of a stolen item is irrelevant: Temple Thieves, abductors and robbers are executed, the city compensates lost items if the robber escapes
    – Trish
    Jan 24, 2022 at 20:34
  • @Trish Is the Philosophy (something Metaphysical/not Empirical) system dependent? If I was pressured on stating a system in mind I would state the German or French systems. But I believe that philosophy is invariant so that is why I believe it was not important. Because it is not about what a French or a German judge does but about the treatment in law of the philosophical issue of value. Jan 24, 2022 at 20:42
  • @Trish Ι don't understand how the question is not clear. Feb 12, 2022 at 16:55

2 Answers 2


The law does not deal with a judge who wants to be consistent with Economics and coincidentally also is a B.A in economics. The law just deals with judges, irrespective of their desires. The law simply tells the judge "Follow the law" – what constitutes following the law differs from jurisdiction to jurisdiction. This is so whether the issue is statutory interpretation or the determination of loss in a contract dispute, or some issue touching on the notion of "profound injustice".

In the US, this is the basic rule regarding admissibility of expert testimony. It starts:

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if

Then the court must decide whether a particular witness satisfies the conditions. The criteria are that the specialized knowledge will help the trier of fact, and is based on sufficient facts, and appropriate to your question

(c) the testimony is the product of reliable principles and methods; and

(d) the expert has reliably applied the principles and methods to the facts of the case.

Note that the sociology of a method is not an explicit component of this rule. In fact, voiceprint evidence is still admissible in many US jurisdictions although it has been thoroughly rejected in the scientific community. Evidence that is admitted which goes against the interests of one party is stiff defeasible under US law.

If a witness is to testify solely to a self-evident fact that is not disputed, the witness' testimony is irrelevant because it does not help the trier of fact.

  • Let's say that some statute says award the value,(i.e award the amount of money that something (that thing) would be bought or sold). Any statute that would require the judge to find out the value of something does the job it was just an example. The Judge appoints an expert and the expert report has mistakes in both methodology and philosophy (it doesn't follow the lex artis of Economics). Can the Judge examine the methodology and the philosophy of the expert report (whether it followed lex artis) or can he only examine the honesty of the expert alone and accept the expert report in toto? Jan 24, 2022 at 22:47
  • Do you want more details on expert testimony under US law? Judges don't appoint experts, they rule on the admissibility of expert testimony.
    – user6726
    Jan 24, 2022 at 23:09
  • @GeorgeNtoulous which is where the legal school and jurisdiction come in: what is gob of a judge and what they may not do is jurisdiction based.
    – Trish
    Jan 25, 2022 at 7:25
  • @user6726 Is the admissibility all or nothing? Can they only either accept the expert report in its totality or dismiss it in its totality? What happens when the expert is honest but their methodology is faulty or when they have fallacies? Can the judge check it too? Jan 25, 2022 at 8:01
  • Ι don't understand how the question is not clear. Feb 12, 2022 at 16:55

The judge considers the evidence presented and the law

Any judge that brings in evidence that neither party has contended is in error.

In common law jurisdictions, the purpose of a lawsuit is to resolve the dispute between the parties using the evidence that the parties submit: the judge is not there to introduce things the parties don't submit.

If the parties agree that value is objective or that pigs can fly, then the court accepts that, for this case, those things are facts. If there is a dispute on these facts, then each side presents evidence that supports their position and on the evidence and only on the evidence, the judge decides which party has proved their position - a judge should not substitute personal knowledge for evidence.

Similarly, just because the current paradigm among economists is that value is relative or the paradigm among chemists is that fire is hot is irrelevant. Each side can introduce evidence (probably expert evidence) on the relativeness of value or the hotness of fire and where those experts disagree (as they invariably do), the judge decides whose evidence they prefer.

That does not mean that a judge who is an expert in another field cannot utilise their expertise but that should be constrained to asking the parties to bring evidence. For example: "You guys are arguing on the basis the value is objective but you haven't submitted any evidence that the court should accept that premise, rather than the alternative that it's relative. Can you make submissions on this matter or agree that for this case you want the court to treat value as objective?"

  • If there is a dispute that there was a Presidential Election in 2020 or on the current day (what date is today) can the judge only decide on the evidence? Can they substitute common knowledge, rules of physics/rules of nature, common sense? Jan 25, 2022 at 8:14
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    @GeorgeNtoulos Yes. No. If the parties are disputing the fact that there was an election then that is a matter that must be decided on the evidence. If the parties agree that there wasn’t one, then the case proceeds with that as an established fact. Common law courts are not interested in capital T truth - that’s for philosophy, not law - they only exist to resolve the dispute.
    – Dale M
    Jan 25, 2022 at 9:49
  • And let's say there really is dispute (there is no agreement that there wasn't an election on 2020) but the party with the stronger evidence is actually false (the Judge knows it because these are the rules of nature, common knowledge). Are they still forbidden from using it? Civil Procedure is about the formal (not substantial/not in content) truth so if the parties agree we are fine (whatever they agree to is a fact) but when there is dispute there seems to be space for common knowledge and rules of nature to be evidence. Jan 25, 2022 at 9:56
  • Most jurisdictions uphold that only facts are subject to evidence and iura novit curia (the Court knows the Law and that is not a matter of evidence/matter of fact any opinions may only persuade the court and they are not evidence) and have Common Knowledge and Rules of Nature in their Rules of Evidence. These same jurisdictions (that allow for Rules of Nature and Common Knowledge to be Evidence even if no one adduces them) seem to expect the Court to appoint an Expert and accept whatever they say as long as they are honest even if they make blatant mistakes in the methodology of their Report. Jan 25, 2022 at 10:04
  • Ι don't understand how the question is not clear. Feb 12, 2022 at 16:55

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