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The Daubert Worldview

    "To summarize: 'general acceptance' is not a necessary precondition
   
to the admissibility of scientific evidence under the Federal Rules
    of Evidence, but the Rules of Evidence -- especially Rule 702 -- do
    assign to the trial judge the task of ensuring that an expert's testimony
    both rests on a reliable foundation and is relevant to the task at hand.
"

    -- Blackmun, J., in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)

Chapter 2: Daubert in a Nutshell

    The Supreme Court's decision in Daubert lends itself to brisk summary.

    For many years, the admissibility of expert scientific evidence was governed by a common law rule of thumb known as the Frye test, after a 1923 decision by the District of Columbia Court of Appeals in which it was first articulated.  Under the Frye test, expert scientific evidence was admissible only if the principles on which it was based had gained "general acceptance" in the scientific community.

    Despite its widespread adoption by the courts, this "general acceptance" standard was viewed by many as unduly restrictive, because it sometimes operated to bar testimony based on intellectually credible but somewhat novel scientific approaches.

    In Daubert, the Supreme Court was asked to decide whether the Frye test had been superceded by the adoption, in 1973, of the Federal Rules of Evidence.  After all, Fed. R. Evid. 702, the rule broadly governing the admissibility of expert testimony, did not even mention "general acceptance," but simply provided: "If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise."

    The majority opinion in Daubert, authored by Justice Blackmun, held that Rule 702 did indeed supplant Frye.  This did not mean, however, that all expert testimony purporting to be scientific was now to be admissible without further ado.  Rule 702 did require, after all, that the testimony actually be founded on "scientific knowledge."  This implied, according to the Court, that the testimony must be grounded in the methods and procedures of science -- a.k.a. "the scientific method."  Evidence thus grounded, said the Court, would possess the requisite scientific validity to establish evidentiary reliability.  

    The Court also noted Rule 702's requirement that expert testimony assist the trier of fact.  This, according to Daubert, was primarily a question of relevance or "fit."  The testimony must be sufficiently tied to the facts of the case, the Court held, to aid in the resolution of an issue in dispute.

    The Court explicitly refused to adopt any "definitive checklist or test" for determining the reliability of expert scientific testimony, and emphasized the need for flexibility.  The Court did list several factors, however, that it thought would commonly be pertinent:

bulletwhether the theories and techniques employed by the scientific expert have been tested;
bulletwhether they have been subjected to peer review and publication;
bulletwhether the techniques employed by the expert have a known error rate;
bulletwhether they are subject to standards governing their application; and
bulletwhether the theories and techniques employed by the expert enjoy widespread acceptance.

    By way of offering further guidance, the Court emphasized that the admissibility inquiry must focus "solely" on the expert's "principles and methodology," and "not on the conclusions that they generate."

    To assuage fears that its ruling would result in a "free for all" in which juries would be confounded by "absurd and irrational pseudoscientific assertions," the Court emphasized the continued availability of traditional tools under the adversary system, including vigorous cross-examination, presentation of contrary evidence, and careful instructions to jurors on burdens of proof.  The Court also noted the availability of other mechanisms of judicial control, including summary judgment and the ability to exclude confusing or prejudicial evidence under Fed. R. Evid. 403.

    In response to the fear that its new evidentiary standards would sometimes stifle courtroom debate, the Court acknowledged that those standards would occasionally prevent juries from "learning of authentic insights and innovations," but concluded that such was the inevitable consequence of evidentiary rules "designed not for the exhaustive search for cosmic understanding but for the particularized resolution of legal disputes."

    All of that is straightforward enough.  Right?

Next: Chapter 3 -- Daubert Misinterpreted

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Prolegomenon
Chapter 1
Chapter 2
Chapter 3