Also known as: gatekeeper role · gatekeeping roles · gatekeeper roles · judicial gatekeeping · gatekeeper function
Written by attorneys — see sources below.
A judicial function performed by trial courts to screen proposed expert testimony for reliability and relevance before it reaches the jury. The court must determine whether the opinion rests on sufficient facts or data, employs reliable principles and methods, and applies those methods reliably to the case at hand. An appellate court reviews the trial court's decision for abuse of discretion.
Gregory Gates sued a chemical manufacturer after developing a respiratory illness. His expert linked the illness to the defendant's product by citing animal studies and general exposure data. The district court found too great an analytical gap between the data and the expert's specific causation opinion and excluded the testimony. On appeal the circuit court affirmed, holding that the exclusion fell within the trial court's discretion.
Gretchen Graham alleged birth defects caused by a prescription drug. She offered experts who claimed their methods were generally accepted in the field. The trial court required objective validation of the methodology rather than accepting the experts' assurances and excluded the testimony. The appellate court upheld the ruling as a proper exercise of the gatekeeping function.
Two minors brought suit against Merrell Dow Pharmaceuticals, claiming they suffered limb reduction birth defects because their mothers had taken Bendectin, a drug prescribed for morning sickness to about 17.5 million pregnant women in the United States between 1957 and 1982. Limb reduction defects occur in fewer than one birth out of every 1000. Scientists do not know the mechanism by which any teratogen causes such defects. The plaintiffs offered testimony from three groups of experts. One group proposed to testify to a statistical link between Bendectin ingestion during pregnancy and limb reduction defects based on reanalyses of published studies that had reported no such association. A second group proposed to testify that Bendectin causes limb reduction defects in humans because it causes such defects in laboratory animals. A third group proposed to testify based on the similarity of Bendectin's chemical structure to other drugs suspected of causing birth defects. The district court granted summary judgment to Merrell Dow after excluding the plaintiffs' expert testimony. The Ninth Circuit affirmed that decision. The Supreme Court granted certiorari, reversed, and remanded for consideration under Federal Rule of Evidence 702. On remand, the Ninth Circuit examined the affidavits and prior trial testimony of the plaintiffs' experts. None of the experts had studied the effect of Bendectin on limb reduction defects before being hired to testify in this or related cases. None had published his work on Bendectin in a scientific journal. The only review their work had received was by judges and juries. Plaintiffs' epidemiological experts made vague assertions of a statistically significant relationship between Bendectin and birth defects but did not state that the relative risk exceeded two. With the exception of Dr. Palmer, the remaining experts were willing to testify only that Bendectin is capable of causing birth defects. Dr. Palmer alone was willing to testify that Bendectin did cause the limb defects in each of the children, based on his review of the plaintiffs' medical records and his conclusion that Bendectin is a teratogen.
View caseThe court must decide whether the expert's opinion rests on sufficient facts or data, whether the expert employed reliable principles and methods, and whether those methods were applied reliably to the facts of the case.
Appellate courts review a district court's decision to admit or exclude expert testimony for abuse of discretion.
Supporting sources
Yes. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered and may exclude the testimony on that basis.
Supporting sources
…by people who deal in these matters, see, e.g., Gross Aff. at 5. The Court held, however, that federal judges perform a "gatekeeping role," Daubert , --- U.S. at ----, 113 S.Ct. at 2798; to do so they must satisfy themselves that scientific evidence meets a certain standard of reliability before it is admitted. This means…