Chapter 2 Emergence of the Standards Governing Expert Witnesses

• Jurisdiction: United States

Chapter 2 Emergence of the Standards Governing Expert Witnesses

A. Deference to the Scientific Community Under Frye

For much of the 20th century, federal courts determined the admissibility of expert testimony according to the evidentiary standard established by Frye v. United States⁸ and its progeny. That standard was created at a time when screening "junk science" and other unproven evidentiary theories was a major jurisprudential concern. In a short, citation-free opinion, the D.C. Circuit Court of Appeals held that an expert opinion relating to a particular scientific theory or technique is inadmissible unless the relevant scientific community deems it "generally accepted."⁹ In Frye, the court determined that a systolic blood pressure deception test — a precursor to the polygraph test — was not generally accepted by the scientific community, therefore any expert opinion derived from the technique was per se inadmissible.¹⁰ Under the Frye standard, courts addressing similar admissibility questions accorded great deference to the "relevant scientific community," thus avoiding a direct confrontation with scientific uncertainty.

B. Judicial Independence Under Daubert

Though criticized by commentators and courts for approximately 70 years, the "generally accepted" test was still the dominant standard used to determine admis-sibility in 1989 when infants and their guardians sued Merrell Dow Pharmaceuticals Inc.¹¹ alleging that its anti-nausea drug, Bendectin, caused birth defects when the drug was taken by pregnant women. In that case, the defendant's experts were prepared to testify that no epidemiological studies showed any causal link between the drug and birth defects. The plaintiff's experts, in juxtaposition, drew a causal link through chemical structure analysis, animal studies, and the unpublished "reanalysis" or "meta-analysis" of previously published epidemiological studies.¹²The district court granted the defendant's pre-trial motion for summary judgment, finding the opinion of plaintiffs' experts inadmissible:

The federal courts have held that epidemiological studies are the most reliable evidence of causation in this area. Accordingly, expert opinion which is not based on epidemiological evidence is not admissible to establish causation because it lacks the sufficient foundation necessary under FRE 703.¹³

The plaintiffs appealed to the Ninth Circuit Court of Appeals, arguing that reanalysis was, in fact, a generally accepted scientific method.¹⁴ The Ninth Circuit affirmed the district court's decision, stating that "reanalysis of epidemiological studies is generally accepted by the scientific community only when it is subjected to verification and scrutiny by others in the field."¹⁵ Because the reanalysis relied upon by the plaintiff's experts had been developed for litigation, had not been published and had not been subjected to peer review, it was upheld as inadmissi-ble.¹⁶ At the time, other Bendectin-related lawsuits were proceeding throughout the country relying on virtually the same evidence; in reaching its ruling, the Ninth Circuit echoed three other circuits that had found similar testimony inadmissible¹⁷ and noted that the only contrary decision came from the Third Circuit Court of Appeals, which had expressly disavowed the "generally accepted" test¹⁸ and was thus inconsistent with Ninth Circuit precedent.¹⁹

Recognizing the conflict among the circuits, the Supreme Court granted certiorari to determine the standard for the admissibility of scientific evidence. Before the Supreme Court, the plaintiffs argued that the Frye test was superseded by the more recently adopted Federal Rules of Evidence. The Court agreed,²⁰ first discussing the application of the Federal Rules of Evidence to the admissibility of expert testimony and the role of the district court in reaching that determination. The Court ruled that the standard for admissibility under the Federal Rules of Evidence was a liberal one under which all relevant evidence is admissible, with relevance determined by reference to Federal Rule of Evidence 401.²¹ The Court further noted that the Federal Rules of Evidence contained a specific provision, Federal Rule of Evidence 702, governing expert testimony, and that the rule did not include any reference to, nor did it specifically incorporate, the "general acceptance" standard — which is otherwise contrary to the liberal thrust of the Federal Rules of Evidence.²²

After determining that the Federal Rules of Evidence, rather than the "general acceptance" test, governed the admissibility of expert testimony, the Court discussed the role of the trial court in screening expert testimony, stating that the trial court must ensure that scientific testimony is both "relevant" and "reliable."²³ For evidence to be "relevant," it must relate to an issue in the case and assist the trier of fact in understanding evidence or a fact.²⁴ In sum, the question of relevance is one of "fit" — that is, Does the proposed evidence fit into the parameters of the questions presented by the case?²⁵

After determining that the evidence is "relevant," the trial court must next determine if the proffered evidence is "reliable." Among the factors to be considered when determining the reliability of a scientific theory or technique are (1) whether it can be or has been tested, (2) whether the theory or technique has been subject to peer review or publication, (3) the known or...