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by Anne M. Gaeta and Elizabeth A. Sitnick - Harvard Law School '99
In 1923, the Supreme Court established "general acceptance" as the standard of admissibility for expert scientific testimony.(1) This standard required only that the judge defer to the opinions of scientists, so long as those opinions were consistent with conventional scientific wisdom. Seventy years later, the Supreme Court's decision in Daubert v. Merrell Dow Pharmaceuticals required the judge to determine the reliability of an expert's testimony based on the judge's own assessment of the methodology used.(2) Apparently, while judges are to apply objective criteria in evaluating a scientific explanation, they ultimately need to make a subjective decision about whether the testimony is reliable. However, if the gatekeeping responsibility is framed as an obligation to exclude unreliable evidence rather than to decide what constitutes "good" scientific testimony, the role of the judge is more manageable.
Determining Admissibility of
Scientific Evidence: From Frye to Daubert
Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deducted from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.(4)Until 1993, the Frye "general acceptance" test was the governing law in federal courts regarding admissibility of scientific evidence.
Frye involved a novel technique that was introduced as evidence of an individual's guilt or innocence. But as scientific technology improved and experts used mainstream techniques in unfamiliar territory or to achieve unusual results, the distinction between proven methodology and novel experimentation blurred. In large-scale tort cases, for example, expert testimony was used to prove subtle issues, such as increased probability and causal links between exposure to an agent and incidence of a disease.
Increasing Use of Expert Scientific
Testimony in the 1980's
Today, virtually any doctor armed with a medical degree can testify. . . He need not establish that his diagnostic methods or logical leaps enjoy "general acceptance" among other doctors. Quite the contrary: he may insist that he alone among doctors understands the importance or origins of certain symptoms.(5)Before Daubert, in response to the above concern, judges shaped their gatekeeping roles in order to prevent the jury from hearing questionable expert testimony. In 1985, Judge Weinstein addressed the claims of Vietnam veterans who opted out of the class created in the Agent Orange litigation.(6) Weinstein rigorously reviewed plaintiffs' causation evidence and granted defendants' summary judgment motion.(7)
An en banc Fifth Circuit decision in Christopherson v. Allied-Signal stated that for expert testimony to be admissible, its conclusion must be supported by well-founded methodology.(8) But this was just one requirement in a four-part test, which the majority claimed grew naturally out of Frye and the FRE.(9) The concurrence and dissent stated that the majority manipulated the precedent and rules in order to exclude far more evidence than was permitted under the FRE.(10) Thus, Judge Weinstein in the Agent Orange litigation and the majority in Christopherson reacted against a perceived tendency in the 1980's for judges to accept a very broad range of expert scientific testimony, without looking more closely at its inherent validity.
The Daubert Holding
[T]he reliability of a scientific technique or process does not vary according to the circumstances of each case. It is therefore inappropriate to view this threshold question of reliability as a matter within each trial judge's individual discretion.(12)The Supreme Court granted certiorari "in light of the sharp division among the courts regarding the proper standard for admission of expert testimony."(13) The Court applied the Federal Rules of Evidence (FRE), Rules 402 ("all relevant evidence is admissible") and 702, governing expert testimony:
[I]f 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.(14)The Court further noted that:
Nothing in the text of [these rules] established "general acceptance" as an absolute prerequisite to admissibility . . . the drafting history makes no mention of Frye, and a rigid "general acceptance" requirement would be at odds with the "liberal thrust" of the Federal Rules and their "general approach" of relaxing the traditional barriers of "opinion" testimony.(15)The Supreme Court found that the FRE, adopted in 1975, superseded the 1923 Frye decision.
The Supreme Court's mandate created a more flexible (standard-based) approach allowing the judge to conduct his own analysis of the expert's claims. By requiring that judges look more closely at scientific testimony, the holding in Daubert substantially alters the gatekeeping role of judges. First, judges are required to determine not only whether the testimony is relevant to the case at hand, but also whether it is reliable. Second, to make the determination about reliability, the judge himself has the responsibility for quality control, rather than the scientific community, which under Frye dictated what techniques, were "generally accepted."
Interpreting the Gatekeeping
Some states did not adopt the Daubert test for fear that it was too liberalizing. For example, in 1994 the Supreme Court of California rejected the Daubert test.(18) Instead, the court reaffirmed its allegiance to Frye by using the test to evaluate the admissibility of a horizontal gaze nystagmus field sobriety test.(19) The court observed that Frye has several advantages:
(1) assuring that those persons most qualified to asses the validity of a scientific technique would have the determinative voice, (2) providing a "minimal reserve of experts" to critically examine each technique in a particular case, (3) promoting uniformity of decision based on finding a consensus in the scientific community, and (4) protecting the parties by its "essentially conservative nature."(20)Therefore, in California, Daubert is considered a liberalizing test and thus judges prefer the more "conservative" Frye analysis set forth in their Kelly decision.
Gatekeeping: A Decision About
the Exclusion of Testimony, Not a Certification of Valid Science
See Frye v. United States, 293 F. 1013 (D.C. Cir. 1923). See
also John M. Kobayashi,
"Scientific" Expert Opinion Testimony: Qualification
and Admissibility Standards Upon and After Daubert v. Merrell Dow Pharmaceuticals,
Inc., 32 A.L.I.-A.B.A. 27, 45 (1995).
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