On January 15, 2014, the United States Court of Appeals for the Ninth Circuit issued an en banc opinion highlighting the importance of the trial court's gatekeeping responsibility under Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

In Estate of Barabin v. AstenJohnson, Inc., the en banc Ninth Circuit vacated a jury verdict and remanded the case for retrial based on the district court's abuse of discretion when it failed to make the necessary findings of relevancy and reliability under Daubert and Federal Rule of Evidence 702 before allowing the plaintiffs to present expert testimony to the jury.

The underlying case involved a claim that occupational exposure to asbestos in dryer felts used in a paper mill caused mesothelioma in the plaintiffs' decedent. The district court initially excluded the testimony of one of the plaintiffs' causation experts based upon the expert's "dubious credentials and lack of expertise." However, after considering the plaintiffs' motion for a pretrial Daubert hearing, the court reversed its earlier decision excluding the expert because "the plaintiffs did a much better job of presenting to me the full factual basis behind [the expert] testifying and his testimony in other cases," although the court denied the Daubert hearing. With respect to a second causation expert, the district court expressed concern about the differences between the conditions of the expert's tests and the conditions at the paper mill, but allowed the expert to testify provided that the jury was informed of the differing conditions. The district court also allowed expert testimony on the theory that "every asbestos fiber is causative" of mesothelioma, despite a lack of scientific consensus on that issue, "[in] the interest of allowing each party to try its case to the jury."

The en banc Ninth Circuit noted that the reliability inquiry required by Daubert is flexible and gives the trial court wide latitude in determining the appropriate form of the inquiry. Even so, the court held that the trial court must make an assessment of the "scientific validity or methodology" of the proposed testimony, and that the trial court can neither abdicate its role as a gatekeeper, nor delegate that role to the jury. Appellate courts have the authority to determine whether the expert testimony is relevant and reliable, but the court declined to do so in this case because the record was too sparse. Having found that the district court's abdication of its gatekeeper role was not harmless error because the admitted evidence was critical to the plaintiffs' case, the court remanded the case for a new trial. Notably, the majority opinion also rejected the dissent's suggestion that the case be conditionally vacated and remanded to the trial court for a post-hoc Daubert hearing. By remanding the case for a new trial, the en banc Ninth Circuit highlighted the importance of the trial court's gatekeeping function for expert testimony.

The underlying case, Estate of Barabin v. AstenJohnson, Inc., is docketed as case number 10-36142 in the Ninth Circuit, and case number 2:07-cv-1454 in the District Court for the Western District of Washington. The opinion can be found here