# Popular Science Monthly/Volume 33/September 1888/Expert Testimony

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* EXPERT TESTIMONY.
By Professor FRANK W. CLARKE.
OF all the causes which tend to discredit science, not one is more mischievous than the policy of the courts with regard to "expert testimony." Whenever a question of scientific fact or theory becomes involved in the settlement of a lawsuit, a swarm of "professional" witnesses are called, who testify on opposites sides, until neither judge nor jury can tell what is or is not really settled. Of these witnesses some are trained, some untrained; some are competent, some incompetent; some are scrupulous, others are unprincipled; and no sure rule of discrimination is properly applied between them. As a rule, all, though sworn, are expected to act like paid attorneys, each serving the side which employs him; and the one supreme test of capacity is that of shrewdness under cross-examination. Strange perversions of science thus get before the courts, to receive equal weight with worthy evidence; doubts are raised or exaggerated, and facts are misstated or suppressed. The highest scientific authorities, the men whose researches create science, are therefore averse to testifying, and rarely appear in the witness-box; for they can not risk their reputations upon one-sided or partisan statements, nor do they like the misrepresentations into which their evidence may be unscrupulously distorted. Under the present usage the expert bears witness for one side against the other; whereas the truth, being "neither black nor white, but gray," may stand in the middle of the disputed territory. The science of the court-room is litigious, not judicial; and no place is found for the unbiased presentation of fact, regardless of its bearing upon the personal interests at stake, and with fair credit given to genuine doubts and uncertainties. To the scientific partisan the court-room doors are wide open; to the scientific jurist they are practically closed, for no one wants his services. In criminal cases, perhaps, a better showing may be made; for here we have an impersonal state seeking to do exact justice, and its experts have no private ends to gratify. If, however, they are incompetent, the criminal, perhaps a poisoner, may escape punishment; and glaring cases of this kind are on record. Any experienced chemist can easily cite examples in point, for prosecuting attorneys are not always able to distinguish between true and false experts, and the latter sometimes destroy the evidence of crime in their blundering efforts to detect it.
Most men of science, and indeed most professional men, have two reputations—the one within, the other without the ranks of their colaborers. The two are rarely, if ever, quite ​commensurable, for popular repute may vary widely from true professional standing, and the quack is often better known to the world at large than the man of really solid attainments. There are quacks in science, just as elsewhere, and these men sometimes have prodigious popular reputations. One of them, widely known as an expert in the courts and on the certificates of patent-medicine venders, was once called upon to analyze a commercial product. "Do you want this sample analyzed to buy or to sell?" was his modest inquiry! Still another class of experts, having creditable standing among their fellows as regards knowledge and ability, is made up of men to whom a science is a trade rather than a profession; a business in which money is to be made, decently and honestly of course, but with no place in it for sentimentality or unselfish devotion to abstract principles. They enter the court-room, as do the lawyers, to win cases for their clients; not by unfair means or trickery, but by the strongest presentation of the favorable evidence. To present, as expert witnesses, the whole argument, pro and con, is not their recognized function. They answer certain questions, which have been carefully agreed upon beforehand; they evade opposing questions as far and as adroitly as possible; but science itself is not a client, and has no true representative in the court.
It goes almost without saying that, if science is to grow and flourish, it must be esteemed and respected by the community. Its advocates, therefore, to protect themselves, must oppose every policy which tends to its disparagement. Nearly every trial in which experts are called is harmful to the interests of science, for its supposed representatives too often forget their duty, and a feeling is spread abroad that all its conceptions are fanciful and uncertain. The disputes of litigation do not add to its dignity. It is, of course, impracticable to abolish expert testimony, even of the crudest and most venal kind; for each side in a suit has the manifest right to submit whatever evidence it can get in its own favor. The problem is, to modify the evil, and to reduce its influence to a minimum. How can this best be accomplished?
From what has already been said it will be easily seen that the position of an expert is different from that of an ordinary witness. The latter testifies to facts which, bearing directly upon the case under trial, are part of his personal knowledge, independently of all abstractions or. principles. He has seen a murder committed, he identifies a person or a signature, he met a certain man at a certain time or place, and the like. On most of these points the testimony of the most ignorant laborer is as good as that of the highest scholar, for they relate to the narrowest and simplest kinds of experience, and involve no mental training whatever. The expert, on the other hand, is nearer akin to the ​attorney; lie testifies to matters which involve more than bare facts, which require special training, and reach out into points of delicate judgment, careful interpretations of evidence, and statements of what is or is not received as scientific opinion. The ordinary witness is well within the range of experience of every man on the jury; the expert speaks of regions into which the jurors have never entered. He testifies, but he also cross-examines, albeit by proxy: for he supplies the lawyers on the same side with himself with questions for the confounding of his adversary. The attorney is merely a legal expert who argues a case for his client, but is not sworn to speak the truth; the expert witness argues, but under an oath which admits of reservations. The two are different in matters of form, but not in matters of practice. They are, in short, colleagues.
Now in the organization of the courts the legal elements have a position of peculiar advantage. First, there are the opposing lawyers, who were once examined for admission to the bar, and who may be disbarred for unworthy or unprofessional conduct. Each argues his case in favor of his client, raising a legal fog or clearing away confusion according to which policy is the better. But over them is the bench, with its trained experts sitting in judgment on the case, deciding all principles of law as controversy arises, listening to and weighing the arguments, and finally, in jury trials, addressing a charge to the jury. The legal questions are discussed by legal experts, and decided by impartial legal arbiters; but the scientific problems which come before a court are subjected to no such arbitration. Just here a line of reform is plainly indicated—not as to the final settlement of scientific questions, of course, but at least as to their proper presentation before judges and juries. Between opposing experts only experts can decide.
Two measures at once suggest themselves: First, that all experts who desire court-practice should be registered, or go through some form of admission to practice, in such a way as to certify in a measure to their having received a proper scientific training. The time of the courts should not be wasted by scientific dabblers or amateurs. Experts should also be liable to something like disbarment for sufficient cause. Secondly, whenever the parties to a suit bring in expert testimony, the court itself should have the right to summon other experts, who, standing in a semi-judicial and non-partisan position, could listen to evidence and arguments, weigh both, and aid the judges either in the preparation of their opinion, or in framing their charge to the jury. So, just as the legal experts pass upon matters of law, the scientific experts would pass upon matters of science, and the results could not be other than favorable. Pretenders, getting less easily before the courts. ​would testify less confidently if they knew that all their statements were to be properly reviewed; science itself would be more fairly represented, public interests would be subserved, and charlatanry would be the only sufferer.