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by Daniel S. Fridman and J. Scott Janoe - Harvard Law School '99
Expert witnesses have become fixtures in today's courts. From fiber comparisons to economic projections to psychiatric evaluations, the range of offered expertise covers the span of human knowledge. Hardly a case of any consequence goes to trial without expert testimony of some kind. With such widespread use of expert testimony comes the inevitable question: "what is the trial judge's role in overseeing the testimony of expert witnesses?" Unlike lay witnesses, whose testimony a jury can evaluate based on their own common sense and experience, expert witnesses offer conclusions based on practices and knowledge beyond the ken of the average juror. As a consequence, testimony by unpoliced expert witnesses can have a potentially prejudicial effect on jurors, who may be inclined to believe the experts solely because of their "expert status." How is the trial judge to know whether the expert is merely speculating, or whether the evidence on which the expert bases his or her conclusions is sufficient to support the conclusion? Judges certainly prevent lay witnesses from speculating and are expected to exclude the testimony of a witness offering wholly speculative evidence. Why should this mandate be any different when the witness purports to be an expert?
If one accepts the proposition that the trial judge has a duty to exclude unreliable experts, a host of concerns inevitably follows. How is a trial judge to assess the scientific or technical adequacy of expert testimony if even a cursory understanding of the issues requires specialized training? Can anyone without such training fully understand the issues and come to a rational conclusion as to their validity? To what degree can the trial judge rely on the expert's own assertions about his or her qualifications? All of these concerns carry heavy weight for in many cases the trial judge is hardly a more qualified assessor of scientific credibility than the jury itself. In this introduction and the papers which follow it, we have laid out some possible answers to the myriad questions raised by judicial gatekeeping. This first paper attempts to establish a historical perspective on gatekeeping in California. The papers which follow it give a more generalized picture of the gatekeeping debate. Ultimately we hope that you find these materials helpful in formulating or fine tuning your own approach to science in the courts.
From Frye to Daubert:
Judicial Gatekeeping in the Federal Courts
With the adoption of the Federal Rules of Evidence in 1975, courts, scholars and practitioners alike began to question whether Fryewould survive as the sole admissibility standard for expert testimony. Under the Federal Rules, judges were seemingly afforded more discretion in making admissibility determinations. Rule 104(a) assigns judges the responsibility of making a preliminary determination on whether to allow a given expert to testify. Rule 702 goes on to guide this decision by requiring the judge to determine whether the admission of such testimony will assist the trier of fact to understand evidence or determine a fact at issue. Finally, Rule 403 suggests that the judge may exclude evidence if its likely prejudicial effect outweighs its probative value. The question was then to what degree would the arguably conservative Frye general acceptance standard survive in the wake of the presumably more liberal admissibility framework embodied in the new Federal Rules of Evidence.
The U.S. Supreme Court endeavored to answer the question of Frye's continued viability in Daubert v. Merrell Dow Pharmaceuticals, Inc.(3) In Daubert the Court held that Rule 702 did in fact supersede the Frye standard and enumerated a new standard to instruct judges on how to act as judicial gatekeepers. This new approach consisted of a two-pronged analysis of the testimony centering on the testimony's reliability and relevance. In determining reliability the court must engage in a, "preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts at issue."(4) In addition, when determining scientific reliability the trial judge should consider:
(1) whether the proffered knowledge can be or has been tested, (2) whether the theory or technique has been subjected to peer review and publication, (3) the known or potential rate of error, and (4) whether the theory or technique has gained general acceptance in the relevant scientific discipline.(5)This nonexhaustive list of indicia of reliability relegated the Frye standard to one of a handful of guidelines that may be employed in ruling on admissibility. In conjunction with the newly ordained relevancy prong, the reliability criteria form a substantially more robust framework with which to analyze given scientific testimony.
Kelly / Frye: California's
[A] beneficial consequence of the Frye test is that it may well promote a degree of uniformity of decision. Individual judges whose particular conclusions may differ regarding the reliability of particular scientific evidence, may discover substantial agreement and consensus in the scientific community. . . . The primary advantage, however, of the Frye test lies in its essentially conservative nature. . . . Frye was deliberately intended to interpose a substantial obstacle to the unrestrained admission of evidence based upon new scientific principles.(8)The Court found the Frye standard to be protective: it protects jurors from being unduly swayed by the impressive nature of testimony which is shrouded in science, it protects the rights of criminal defendants when new science is being used to connect them to the crimes, and it protects the common law in California from containing precedents which would allow the admission of evidence based on dubious scientific grounds.(9)
Logistically, Kelly / Frye requires "a preliminary showing of general acceptance of the new technique in the relevant scientific community."(10) From there, California Evidence Code §§ 720 & 801 take over and require a two step process: "(1) the Reliability of the method must be established, usually by expert testimony, and (2) the witness furnishing such testimony must be properly Qualified as an expert to give an opinion on the subject."(11) This system of admitting scientific evidence has remained virtually unchanged in California, and most notably, survived the United States Supreme Court Daubert decision.
Leahy: The Song Remains
Though not mandated by the Evidence Code, the Kelly / Frye standard has remained viable by the very fact that it was recognized in California a full eleven years after the code was written. As the Leahy Court noted "[w]e were presumably well aware in Kelly that the Frye 'general acceptance' standard arguably was 'absent from and incompatible with' the preexisting California statutory provisions. Nonetheless, we concluded otherwise and found Frye compatible with those provisions, which we cited in our opinion."(21) Accordingly, the California Supreme Court felt confident that "[n]o significant recent developments have occurred in the state since Kelly was decided to justify abandoning its conclusions."(22) The Court demanded proof that the criticisms of Frye cited in Daubert and other sources were warranted.(23)
Foremost among these alleged criticisms of Kelly / Frye was the assertion that "general acceptance" was an overly restrictive, "conservative" standard. In response the Leahy Court stressed the importance of judicial gatekeeping by reiterating the Kelly Court:
Lay jurors tend to give considerable weight to 'scientific' evidence when presented by 'experts' with impressive credentials. We have acknowledged the existence of a '...misleading aura of certainty which often envelops a new scientific process, obscuring its currently experimental nature.'(24)Thus, the Leahy Court concluded that there remained a need for continued judicial caution in accepting evidence developed by new scientific techniques.(25) Moreover, the Court stressed that while the legislature had amended and / or added a number of provisions regarding the admissibility of expert testimony, it had not altered sections 720 or 801 in response to Kelly.(26) Instead of letting judges or juries with little or no scientific background resolve issues of admissibility, the Leahy Court preserved California's reliance upon the scientific community to determine what is valid science.(27) As a result, Kelly / Frye general acceptance remains the law of the land in California.(28)
Joiner and the Future
of Judicial Gatekeeping
The Supreme Court reversed the Court of Appeals and noted that such a "particularly stringent" standard of review was improper in this context:
Thus, while the Federal Rules of Evidence allow district courts to admit a somewhat broader range of scientific testimony than would have been admissible under Frye, they leave in place the "gatekeeper" role of the trial judge in screening such evidence. A court of appeals applying "abuse of discretion" review to such rulings may not categorically distinguish between rulings allowing expert testimony and rulings which disallow it. We likewise reject respondent's argument that because the granting of summary judgment in this case was "outcome determinative," it should have been subject to a more searching standard of review. On a motion for summary judgment, disputed issues of fact are resolved against the moving party -- here, petitioners. But the question of admissibility of expert testimony is not such an issue of fact, and is reviewable under the abuse of discretion standard.(35)The circuit court's "particularly stringent," pro-admission standard was indeed short lived.
In concluding that the district court did not abuse its discretion in excluding the plaintiff's experts, the Supreme Court examined the adequacy of the expert testimony the plaintiff sought to introduce to prove causation. The plaintiff's experts relied heavily upon animal studies to establish proof of causation in humans. The Court found, however, that the plaintiff failed to establish enough of a foundation to support the admissibility of these studies:
Rather than explaining how and why the experts could have extrapolated their opinions from these seemingly far-removed animal studies, respondent chose "to proceed as if the only issue [was] whether animal studies can ever be a proper foundation for an expert's opinion." Of course, whether animal studies can ever be a proper foundation for an expert's opinion was not the issue. The issue was whether these experts' opinions were sufficiently supported by the animal studies on which they purported to rely. The studies were so dissimilar to the facts presented in this litigation that it was not an abuse of discretion for the District Court to have rejected the experts' reliance on them.(36)Finally, the Supreme Court went on to suggest that it was not an abuse of discretion for the district court to demand a closer relationship between the epidemiological studies offered by the plaintiffs and the opinions drawn from them by the experts:
A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered. See Turpin v. Merrell Dow Pharmaceuticals, Inc. 959 F.2d 1349, 1360 (CA 6), cert. denied, 506 U.S. 826, 121 L. Ed. 2d 47, 114 S. Ct. 84 (1992). That is what the District Court did here, and we hold that it did not abuse its discretion in so doing.(37)Upholding a judge's right to exclude given expert testimony on the basis of perceived analytical gaps in the science is an unprecedented broadening of the gatekeeper role. Such a ruling at first seems to run contrary to the "liberal thrust" of the Rules of Evidence as articulated in Daubert. It remains to be seen whether courts will be as deferential when judges exercise their discretion in favor of admissibility of arguably questionable scientific evidence. Whether Joiner will effect California and states like her that have not adopted Daubert also remains to be seen.
F. 1013 (D.C. Cir. 1923).
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