Featured Expert Column –Judicial Gatekeeping of Expert Evidence
A panel of the US Court of Appeals for the Third Circuit (Judges Chagares, Restrepo, and Roth) recently heard oral argument (audio recording here) in an important products-liability case that raises significant questions about the scope of Daubert.
In In re Zoloft Products Liability Litigation, plaintiffs allege that Zoloft—a prescription drug manufactured by Pfizer that is used to treat depression and anxiety—causes cardiovascular birth defects when used by a mother in the early stages of pregnancy. Because ethical concerns prohibit double-blind, randomized studies on pregnant women, research on birth defects must rely on less rigorous observational studies. Common scientific practice dictates that, even when a correlation has been found to be statistically significant within a narrow confidence interval, a single study remains insufficient to establish causation given the potential for random error, bias, confounding variables, or some other flaw with the study. Accordingly, scientists look to whether an observational study’s results can be replicated to determine whether causation exists.
In this case, and as relevant to the appeal, plaintiffs sought to qualify Dr. Nicholas Jewell as an expert witness. Dr. Jewell is a statistician; he does not purport to be an expert in embryology or cardiology. According to Dr. Jewell, the results of eleven published, peer-reviewed epidemiological studies and his own re-analysis of those studies establish a link between Zoloft and cardiovascular birth defects.
After conducting a Daubert hearing, the district court concluded that Dr. Jewell could not testify as an expert. The court found that there were no replicated statistically significant findings from non-overlapping data—that is, confirming results from studies that do not rely on the same populations or underlying studies. It therefore held that Dr. Jewell’s methods were unreliable. In addition, the district court concluded that Dr. Jewell failed to consistently apply his own methods and standards. It explained that “Dr. Jewell’s selective emphasis on trends and general consistency only when such concepts support his opinion is one example of ‘situational science’ which renders his opinion unreliable.” The district court also excluded Dr. Jewell’s testimony under Rule 403.
At the appellate argument, David Frederick of Kellogg Huber argued for plaintiffs that the district court improperly established a rigid, bright-line rule that an expert must present replicable, statistically significant findings. He accused the district court of going “way beyond the normal Daubert gatekeeping role” and “arrogating to [itself] the power to resolve and reconcile a very complicated epidemiological record.” As plaintiffs’ interpreted Daubert, the district court should have allowed the jury to evaluate Dr. Jewell’s testimony with the panacea of cross-examination to cure any confusion. The panel, however, appeared skeptical of this argument, repeatedly peppering Frederick with questions about the record and the scope of Daubert.
By contrast, the panel appeared receptive to defendants’ arguments, asking fewer and less hostile questions. Defendants’ counsel, Mark Cheffo of Quinn Emanuel, easily dispatched plaintiffs’ straw-man argument that the district court established a bright-line rule about the reliability of scientific evidence. Rather than establish a general rule about the admissibility of expert testimony, Cheffo explained, the district court found that, on this particular record, “plaintiffs’ expert failed to reconcile the studies.” Cheffo further emphasized that the district court gave this case significant attention, holding ten days of Daubert hearings. That effort and diligence reinforces the deference that normally is due to trial courts on questions of admissibility. As Cheffo aptly put it, after that many days of hearings, plaintiffs are not entitled to a “Daubert do-over.”
Although it is always perilous to predict the outcome of an appeal from an oral argument, the panel seems likely to affirm the district court’s careful application of Daubert. Or the panel could avoid the Daubert issue entirely by accepting the district court’s alternative holding that the expert testimony was excludible under Rule 403. Although the parties’ briefs focused on the Daubert question, the panel seemed intrigued by that alternative holding, asking whether the decision could be affirmed on that ground alone and whether plaintiffs had waived any challenge to that ruling.