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Reliability and Admissibility Under Daubert

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
     In Frye v. United States, the Court of Appeals of the District of Columbia evaluated the admissibility of evidence resulting from a "systolic blood pressure deception test," a crude precursor to the modern polygraph machine.(3) The court held that:

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
     The increased use of science in courtrooms and the liberal interpretation of FRE 702, encouraging admission of expert testimony that could "assist the trier of fact," resulted in a weaker "general acceptance" test. In the 1980's, critics of increased litigation and of scientists' roles in trials condemned the widespread use of scientific testimony to boost otherwise weak claims. In 1991, Peter Huber lamented what he saw as diminishing standards for expert witnesses:

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
     The plaintiffs in Daubert presented evidence to prove that their mother's ingestion of the anti-nausea drug Bendectin caused their limb reduction birth defects.(11) A California court applied Frye and found the plaintiffs' evidence inadmissible. The Ninth Circuit affirmed the district court decision:

[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 Role
     Courts adopting Daubert interpreted the Supreme Court decision as a reaction to the increasing use of expert scientific testimony in a wide variety of both civil and criminal cases. Regardless of whether the Supreme Court was reacting to this trend, many of the lower courts have used Daubert to restrict the admission of testimony. For example, the District Court of Oregon applied Daubert to eliminate the plaintiffs' use of expert testimony in a case that consolidated several breast implant suits. In this case, the judge rejected expert testimony offered to prove that silicone breast implants cause auto-immune disease and other illnesses.(16) The court viewed Daubert as imposing a significantly higher level of scrutiny than Frye, especially for evidence attempting to prove causation.(17)

     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
     Daubert recommends that trial judges apply certain criteria to evaluate scientific testimony. Although these factors are set forth as objective, in practice they require judges to make subjective determinations. For example, in deciding if a technique is "generally accepted in the relevant scientific community" (now merely one of the factors in a Daubert reliability inquiry), a trial judge must first define the parameters of this "scientific community." The inherent subjectivity involved in these evaluations makes it unlikely that the Supreme Court intended Daubert to give rise to judges' certifying testimony as "good science." It seems more likely that judges are obligated only to prevent the jury from hearing unreliable testimony. Contrary to Justice Rehnquist's dissent in Daubert, the majority did not require judges to act as "amateur scientists," but rather to fulfill a more manageable gatekeeping role that requires exclusion of obviously invalid testimony.(21)

     In placing responsibility for assessing the reliability of expert opinions directly on trial judges, the Supreme Court at one and the same time liberalized the standards of admissibility and enhanced the constraining power of trial judges to exclude unreliable expert testimony. The liberalization inheres in the change in standard from the single criterion of "general acceptance" to a more flexible look at reliability. Opinions based on methodology, which is not generally accepted, but is, nonetheless, reliable can now be admitted. The enhancement of constraint inheres in the charge to trial judges to take responsibility in the quality of admitted evidence.


1. 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).
2. 509 U.S. 579 (1993).
3. 293 F. at 1014.
4. Id. at 47.
5. Peter W. Huber, Galileo's Revenge: Junk Science in the Courtroom 16 (1991).
6. See Peter H. Schuck, Agent Orange on Trial: Mass Toxic Disasters in the Courts (1986).
7. Inre "Agent Orange" Product Liability Litigation, 611 F.Supp. 1223, 1263 (E.D.N.Y. 1985).
8. 939 F.2d. 1106, 1111 (5th Cir. 1991).
9. Id. at 1110. The first step required that the witness was qualified to express an expert opinion. (FRE 702). The second required that the expert relied on facts that are of the same type used by other experts in the field. (FRE 703). The third required that the expert use well-founded methodology. (Frye). The fourth required that the testimony's potential for unfair prejudice did not outweigh its probative value. (FRE 403).
10. Id. at 1116.
11. See Daubert v. Merrell Dow Pharmaceuticals, 727 F.Supp. 570 (S.D. Cal. 1989).
12. 951 F.2d 1128, 1130 (9th Cir. 1991), quoting Reed v. State, 283 Md. 374, 391 (1978).
13. 509 U.S. at 584.
14. Id. at 587, 588.
15. Id. at 587, quoting Beech Aircraft Corp. v. Rainey, 488 U.S. at 169.
16. Hall v. Baxter, No. 92-182, 1996 U.S. Dist. LEXIS 18960 (D.Or. Dec.18, 1996).
17. Id. at *39.
18. See People v. Leahy, 8 Cal.4th 587 (1994).
19. Id. at 591, 593.
20. Id. at 595, quoting Kelly, 17 Cal. 3d at 31-32.
21. 509 U.S. at 600.

Page Last Modified on April 25, 1999 by Dan Fridman - Copyright 1999
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