Daubert v. Merrell Dow Pharmaceuticals

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Daubert v. Merrell Dow Pharmaceuticals (commonly referred to as Daubert) is one of the most important opinions to have come out from the United States Supreme Court. It sets the standard of admissibility of expert witness testimony.


Case Information

Citation 509 U.S. 579; 113 S. Ct. 2786; 125 L. Ed. 2d 469; 1993 U.S. LEXIS 4408; 61 U.S.L.W. 4805; 27 U.S.P.Q.2D (BNA) 1200; CCH Prod. Liab. Rep. P13,494; 93 Cal. Daily Op. Service 4825; 93 Daily Journal DAR 8148; 23 ELR 20979; 7 Fla. L. Weekly Fed. S 632
Judges BLACKMUN, J., delivered the opinion for a unanimous Court with respect to Parts I and II-A, and the opinion of the Court with respect to Parts II-B, II-C, III, and IV, in which WHITE, O'CONNOR, SCALIA, KENNEDY, SOUTER, and THOMAS, JJ., joined. REHNQUIST, C. J., filed an opinion concurring in part and dissenting in part, in which STEVENS, J., joined, post, p. 598. 
Opinion By BLACKMUN 
Opinion Date June 28, 1993

Facts of the Case

This was a products liability case in which the Supreme Court resolved the debate over admissibility standards for scientific evidence in court. Petitioners Jason Daubert and Eric Schuller together with their parents sued Respondent, Merrell Dow in California state court. Petitioners alleged that they were born with serious birth defects which had been caused by the mothers' ingestion of Bendectin, a prescription anti-nausea drug manufactured and marketed by the Respondent, and prescribed routinely to alleviate “morning sickness” during pregnancy. Respondent removed the suits to federal court on diversity grounds. Respondent moved for summary judgment, contending that Bendectin did not cause birth defects in humans. Respondent filed the testimony of Dr. Steven H. Lamm, physician and epidemiologist, who was a well-credentialed expert on the risks from exposure to various chemical substances, in support of its motion. Dr. Lamm stated that he had reviewed all the literature on Bendectin and human birth defects -- more than 30 published studies involving over 130,000 patients. Lamn had opined that no study had found Bendectin to be a human teratogen (i.e., a substance capable of causing malformations in fetuses). Dr. Lamm concluded that the maternal use of Bendectin during the first trimester of pregnancy had not been shown to be a risk factor for human birth defects.

Petitioners filed the testimony of eight experts in response to Respondent's motion for summary judgment. Petitioners’ experts also possessed impressive credentials. They concluded that Bendectin could cause birth defects. Their conclusions were based upon "in vitro" (test tube) and "in vivo" (live) animal studies that found a link between Bendectin and malformations; pharmacological studies of the chemical structure of Bendectin that purported to show similarities between the structure of the drug and that of other substances known to cause birth defects; and the "reanalysis" of previously published epidemiological (human statistical) studies.

In the present case, science could not identify a precise causal mechanism linking Bendectin to birth defects. Statistical evidence derived from epidemiological studies was offered in lieu of more “concrete” evidence, but it was vulnerable to manipulation and produced contradictory conclusions. Respondent claimed that since there was no epidemiological evidence linking Bendectin to birth defects, Petitioners would not be able to offer any kind of “generally accepted” scientific evidence. The lower courts sided with the Respondent and granted Respondent's motion for summary judgment. The lower court invoked a Rule which was more stringent Frye rule. The Frye rule stated that scientific evidence was admissible only if the principle upon which it was based was "'sufficiently established to have general acceptance in the field to which it belongs.'" The court concluded that Petitioners' evidence did not meet this standard. The court further held that the expert opinion which was based on epidemiological evidence was inadmissible to establish causation. Thus, the animal-cell studies, live-animal studies, and chemical-structure analyses on which Petitioners had relied could not raise by themselves a reasonably disputable jury issue regarding causation. Petitioners' epidemiological analyses were based on recalculations of data in previously published studies that had found no causal link between the drug and birth defects. This was ruled to be inadmissible because they had not been published or subjected to peer review.

The United States Court of Appeals for the Ninth Circuit affirmed the judgment of the district court. The Appellate Court declared that expert opinion based on a methodology that diverged "significantly from the procedures accepted by recognized authorities in the field . . . cannot be shown to be 'generally accepted as a reliable technique.'" The Appellate Court concluded that Petitioners' evidence provided an insufficient foundation to allow admission of expert testimony that Bendectin caused their injuries. The court held that Petitioners could not satisfy their burden of proving causation at trial.

Petitioners then appealed the case to the U.S. Supreme Court, asking the Court to resolve the long-standing controversy over whether or not the Federal Rules of Evidence superseded the common law Frye rule as the admissibility standard for scientific evidence in court.

Legal Issues Involved

The main issue involved in this litigation was whether the expert testimony proffered by the Petitioners was admissible. The Court noted that, in order for a testimony to be admissible, expert scientific testimony that is derived from research done for the purpose of litigation must show that the conclusions were reached after following recognized scientific methods of research.

Frye standard had established that expert opinion based on a scientific technique was inadmissible unless the technique was "generally accepted" as reliable in the relevant scientific community. The "general acceptance" test had been the dominant standard for determining the admissibility of novel scientific evidence at trial until the Supreme Court held that the Federal Rules of Evidence superseded Frye as the standard for admissibility of expert evidence in the federal court.

Here Federal Rule of Evidence 702 (Rule 702), governing expert testimony, 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."

Rule 702 now became the standard for admitting expert scientific testimony. Under Rule 702, there are several factors to consider when determining whether expert testimony is admissible:

  • Whether the theory is generally accepted in the scientific community;
  • Whether the theory/method has been subjected to peer review and publication;
  • Whether the theory/method has been tested or can be tested;
  • Whether the potential or known rate of error is acceptable.

It was therefore, the court’s responsibility to resolve disputes among the respected and credentialed scientists about matters within the scientists’ expertise and to reject testimony if it was not obtained by the scientific method.

The court also ruled that if expert testimony was shown to be the result of research conducted for the purpose of litigation, the expert must show precisely how they reached their conclusions and point to an objective source to show that they had followed the scientific method as it was practiced by at least a recognized minority in their field. Since, Petitioners’ experts had failed to do so in this case; their testimony was rendered inadmissible by the Court.

The court also opined that Petitioners’ experts did not conduct their research independent of the litigation and their theories had not been published in scientific journals or reviewed by peers, though there had been ample time to do so because the theories and litigation had been around for a decade.

Furthermore, under Rule 702, the Petitioners must show that the evidence they offered would assist the trier of fact in determining a factual issue. In this case, Petitioners had failed to establish that the defects were not caused by an independent cause, since limb reduction defects had occurred in the babies of mothers who did not take the drug. Petitioners’ experts thus failed to establish that the drug had doubled their risk of the defect; there was only a statistical relationship between the drug and the birth defect.

The change brought about by this case was that nothing in the text of this Rule established "general acceptance" as an absolute prerequisite to admissibility. In this case, the Respondent did not present any clear indication that Rule 702 or the Rules as a whole were intended to incorporate a "general acceptance" standard. Given the Rules' permissive backdrop and their inclusion of a specific rule on expert testimony that did not mention "general acceptance," the assertion that the Rules somehow assimilated Frye was unconvincing. Frye made "general acceptance" the exclusive test for admitting expert scientific testimony. That the Frye test was displaced by the Rules of Evidence did not mean, however, that the Rules themselves placed no limits on the admissibility of purportedly scientific evidence. It did not prohibit the trial judge from screening such evidence. To the contrary, under the Rules the trial judge must ensure that any and all scientific testimony or evidence admitted was not only relevant, but reliable.

Rule 702 clearly contemplated some degree of regulation of the subjects and theories about which an expert may testify. The subject of an expert's testimony must be "scientific knowledge." The adjective "scientific" implied an opinion grounded upon the methods and procedures of science. Similarly, the word "knowledge" connoted a testimony more than subjective belief or unsupported speculation. In order to qualify as "scientific knowledge," an inference or assertion must be derived by the scientific method. Proposed testimony must be supported by appropriate validation -- i.e., "good grounds," based on what is known. In short, the requirement that an expert's testimony pertain to "scientific knowledge" established a standard of evidentiary reliability.

Throughout, a judge assessing a proffer of expert scientific testimony under Rule 702 should also be mindful of other applicable rules. Rule 703 provided that expert opinions based on otherwise inadmissible hearsay were to be admitted only if the facts or data were "of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject." Rule 706 allowed the court at its discretion to procure the assistance of an expert of its own choosing. Finally, Rule 403 permitted the exclusion of relevant evidence "if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury . . . ." Expert evidence could be both powerful and quite misleading because of the difficulty in evaluating it. Because of this risk, the judge in weighing possible prejudice against probative force under Rule 403 of the present rules exercised more control over experts than over lay witnesses.


The Supreme Court was called upon to determine the standard for admitting expert scientific testimony in a federal trial. What lay beneath the technical legal controversy, however, was a host of larger issues pertaining to the relationship of science and law. The crisis ignited by the scientific uncertainty on causation challenged traditional notions of the nature of scientific inquiry, the certainty of its conclusions, and, ultimately, it’s utility in resolving courtroom conflicts.

It is not surprising, then, that when the Supreme Court finally agreed to hear a case pertaining to admissibility standards for scientific evidence, both sides carried their arguments to an extraordinary level. To settle the ongoing debate over admissibility standards, Petitioners called upon their cadre of experts. But these experts were neither more epidemiologists nor chemists, nor even statisticians. They were the physicians, scientists, and historians of science who filed “friend of the court” briefs to the Supreme Court to show how the philosophy of science legitimized their positions on admissibility standards. These briefs had a profound impact on the way in which the Court framed its decision.


The Supreme Court held that Petitioners’ expert testimony was not admissible. The Supreme Court ruled unanimously that the more liberal standard of the 1975 Federal Rules of Evidence superseded the more restrictive standard of the 1923 common law Frye rule.

The Supreme Court clarified that the Federal Rules of Evidence, not Frye, provided the standard for admitting expert scientific testimony in a federal trial. Frye's "general acceptance" test was superseded by the Rules' adoption. The Rules -- especially Rule 702 -- placed appropriate limits on the admissibility of purportedly scientific evidence by assigning to the trial judge the task of ensuring that an expert's testimony both rested on a reliable foundation and was relevant to the task at hand.

Dissenting Opinion

While the Supreme Court was unanimous in its decision that the Frye rule was dead, a minority declined to endorse their recommendations and observations on the relationship between science and law. Chief Justice William Rehnquist and Justice John Paul Stevens preferred not to venture beyond the technical legal question, noting that the briefs in the case dealt not with familiar things like legal precedents or statutory language, but rather with that Rehnquist described as “definitions of scientific knowledge, scientific method, scientific validity, and peer review—in short, matters far afield from the expertise of judges.” By refusing to address the philosophical and functional differences between science and law, the minority ignored the deeper issues embedded in the debate over admissibility standards and left the majority to recast the relationship between science and law.