Q. I'm a property assessor. Being an expert witness is a good source of income, but if I give fair evaluations no one will hire me. Can I tend to low-ball or high-ball estimates in my testimony?

A. The conflict of interest of expert witnesses is a troubling feature of our legal system. In this column, we will discuss the systemic problem and related ethical insights; next week we will turn to your question of how to act within the system.

Modern democracies have an adversary legal system in which each side tries to bring all the available arguments and evidence to support their interest, and then a judge (and sometimes a jury) who will weigh the claims and testimony and reach a conclusion. The system works adequately for claims within the experience of normal individuals, but in many cases the simple evaluation of facts requires some kind of special expertise. This is not limited to cases of advanced scientific knowledge, for example in DNA evidence; it is as just as likely to be normal professional expertise like that of a property assessor. In this case, an expert will be brought in as a witness.

It then works out that in a property case the party suing will shop around for an assessor who tends towards high valuations, and the defending party for one who tends towards low valuations. This is not in itself problematic; trained experts can legitimately disagree and the judge and jury should be made aware of the range of expert opinion.

However, what happens next is that the average, middle of the road assessor suddenly notices that his careful and objective assessment is of little interest to any litigant. An incentive is created to slant the assessment, and this is where the problem begins.

The problem of payment for testimony, and the conflict of interest it creates, is far from new. It is discussed in the Jewish tradition at least from the time of the mishna.

The mishna in tractate Bechorot discusses a person who is an expert in determining when a first-born animal, which is usually dedicated for a sacrifice, becomes unfit for an offering and thus permissible for ordinary use. The mishna states:

One who takes payment for seeing a first-born, it is forbidden to slaughter based on his assessment unless he is a [great] expert like Illa in [the town of] Yavneh, whom the sages permitted to take four isar for each small animal and six for each large one, whether it turned out to be fit or blemished. (1)

The mishna mentions two safeguards. The first is that in normal circumstances we don't permit taking payment for giving a judgment. We are afraid that a person will be tempted to disqualify even fit animals (thus permitting them for consumption) in order to get more business. So an ordinary expert is forbidden to get paid for his evaluation.

But note that there is a second safeguard as well: even in the case of a unique expert, who is allowed to get paid, he must get the same price whether he permits or forbids the animal. The absolute minimum standard is that there shouldn't be any incentive to distort judgment on this particular animal. That still doesn't completely solve the problem because a person who tends to lenient rulings is more likely to get future business, as you have discovered.

Even so, if there is a person of unique expertise and acknowledged judgment, he may be appointed as a designated paid witness. When there is only one great expert, there is no problem of shopping around for one of slanted judgment.

This mishna can help us address the systemic question. First is the question of compensation. At the very least, someone hiring an expert witness should never be allowed to condition any kind of payment on the content of the testimony. Otherwise, we would be sanctioning payment for perjury.

Second is the question of competition. Note that the problem begins with the practice of shopping around for a witness. This practice, while legitimate in itself, leads to perverse incentives for the potential witnesses. If we have a designated witness, appointed by the court itself, this would solve the problem. Such a witness no longer has any incentive to tend to either side in his statements before the court.

I have written before that I believe this idea should be adopted in our legal system. Instead of having each side bring their own witness, there should be some incentive for the sides to agree on one witness, which would strongly favor a professional known for impartiality. Another possibility is for the court to appoint its own expert, which is the closest parallel to Illa of Yavneh.

This is not a perfect or universal solution. In many areas there are fundamental differences of scientific opinion which the judge and jury have to be exposed to. It is not a question of objective or slanted. But in many areas, including property assessment, having a fixed expert or panel of experts could be a fair way of guaranteeing an objective assessment and eliminating the troublesome temptation you mention to distorting judgment.

SOURCES: (1) Babylonian Talmud Bechorot 28b

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The Jewish Ethicist presents some general principles of Jewish law. For specific questions and direct application, please consult a qualified Rabbi.