Federal Standards for Admissibility of Expert Evidence on Causation

THE Federal Rules of Evidence, enacted in 1975, govern the use of expert testimony in federal courts, and they have been adopted or adapted in many states. The Federal Rules were designed in part to broaden the standards for the admissibility of expert testimony. Thus, it is not surprising that the use, and arguably abuse, of expert testimony has increased tremendously since their enactment. Through the years, courts have been increasingly required to make pretrial inquiries into the bases of expert opinions to determine their admissibility. At first, the standards were minimal. If purported experts possessed either the appropriate academic degree or the requisite experience in the subject area, they generally were permitted to testify without any substantive judicial inquiry into the basis or reliability of their opinions. Many federal courts viewed challenges to expert testimony as affecting the weight, not the admissibility of the testimony. In recognition of the critical importance of expert testimony, particularly in the toxic tort area, federal courts finally began to scrutinize proffered testimony to determine admissibility. They have relied on three of the Federal Rules--702, 703 and 403. Rule 702 provides: If scientific, technical, or other specialized knowledge will assist the trier of fact to under- stand the evidence or to determine a fact in is- sue, a witness qualified as an expert by knowl- edge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise. Rule 703 provides: The facts or data in the particular case upon which an expert bases an opinion or inference may be those perceived by or made known to the expert at or before the hearing. If of a type rea- sonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence. Rule 403, the balancing rule, provides: Although relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by consid- erations of undue delay, waste of time, or need- less presentation of cumulative evidence. In addition to the analysis under Rules 702 and 703, federal courts also must scrutinize the proffered testimony under 403 to balance its probative value against the risks of unfair prejudice, confusion of the issues or misleading the jury. Even if testimony satisfies the requirements of 702 and 703, courts have discretion to exclude it under 403. Many courts have held, however, that pretrial exclusions of expert testimony under Rule 403 should be granted rarely. Indeed, the Third Circuit concluded in In re Paoli Railroad Yard PCB Litigation(1) that Rule 403 is a trial-oriented rule. To excluse evidence under it at the pretrial stage, a court must have a complete record on the point at issue, amounting to a virtual surrogate for a trial record. Prior to the Federal Rules, the standard for admission of expert testimony was acceptance, as enunciated by Frye v. United States.(2) The Frye court instructed, While courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which a deduction is made must be sufficiently established to have gained general in the particular field in which it belongs. From the enactment of the Federal Rules in 1975 to the U.S. Supreme Court's 1993 decision in Daubert v. Merrell Dow Pharmaceuticals Inc.(3) there was extensive debate among courts and commentators as to whether the Federal Rules limit or supersede the Frye acceptance standard in favor of a more liberal relevancy standard. …