Magazine article Issues in Science and Technology

Expert Testimony: The Supreme Court's Rules

Magazine article Issues in Science and Technology

Expert Testimony: The Supreme Court's Rules

Article excerpt

Three decisions in the 1990s have clarified the judge's role as the gatekeeper who controls what testimony a jury will hear

At the beginning of the 21st century, it is not surprising that the question of how to handle scientific and technological information in judicial proceedings has moved into the limelight. The explosive growth and importance of scientific and technological knowledge in our society has run a parallel course in the courtroom, where an ever-increasing number of legal disputes cannot be resolved without the assistance of scientific and technological expertise. But although remarkable new scientific findings are reported every day, there is still much we do not know. Consequently, the courts have been struggling with the difficult problem of determining when expertise will actually help the trier of fact (usually the jury but sometimes the judge) in making a determination. An expert witness who claims to have specialized knowledge will be permitted to testify only when that specialized knowledge can really be of assistance. It is in the context of disputes about the admissibility of expert testimony that courts decide what kind of science and technology (S&T) information the legal system will take into account.

One particularly troublesome area for the courts has been the proof of causation in so-called "toxic tort" cases, a subspecies of product liability litigation. These are cases in which the plaintiffs bringing the action allege that their injuries or disease were caused by exposure to the defendant's product. In the past 20 years there has been an enormous increase in toxic tort litigation, which even when it does not result in huge awards (and we all know about asbestos and tobacco) may bankrupt or seriously damage a defendant's financial standing because these suits are so costly to litigate. Except in the case of signature diseases, such as those associated with exposure to asbestos or DES, the injuries of which the plaintiff complains are also found in people who were never exposed to the defendant's product. Consequently, scientific proof that the product in question is capable of causing injuries such as the plaintiff's, and more likely than not did, is crucial.

The use of expert testimony to prove causation has recently captured the attention of the United States Supreme Court, perhaps because of the huge amounts of money at stake or because of allegations that experts in these cases have often relied on "junk science." In any event, since 1993 the Supreme Court has issued a trilogy of opinions dealing with the admissibility of expert proof. Taken together, the trilogy establishes the ground rules for introducing expert testimony in all cases brought in the federal system, criminal as well as civil. Furthermore, although these opinions do not bind state courts, approximately three-quarters of the states have already opted to adopt the Supreme Court's new test, and more will undoubtedly do so in the future. Consequently, anyone who acts in an expert witness capacity in judicial proceedings in the United States is likely to be affected by the trilogy and its progeny.

Not only relevant, but reliable

The first case in the trilogy, Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993), was one of many cases in which plaintiffs claimed that their birth defects were caused by Bendectin, an anti-morning sickness pill that had been taken by their mothers and more than 20 million other women. As a result of the litigation, the defendant manufacturer took the drug off the market even though it never lost its Food and Drug Administration approval. In determining that the epidemiological and toxicological evidence offered by plaintiffs' experts was inadmissible, the lower court in Daubert had applied the so-called "general acceptance" test first enunciated by a federal appeals court in Frye v. United States (1923). The general acceptance test, which was used by some federal courts primarily in criminal cases and is still used by some state courts, conditioned expert testimony about a novel scientific principle on there being a consensus about the theory in the relevant field. …

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