The U.S. Court of Appeals for the 2nd Circuit soon will issue its opinion in In re: Acetaminophen – ASD-ADHD Litigation, a multi-district product liability case where plaintiffs sued several corporations, alleging that maternal prenatal use of acetaminophen caused their children to develop Autism Spectrum Disorder (ASD) and/or Attention Deficit Hyperactivity Disorder (ADHD).
This appeal is important because affirming the district court, Judge Denise L. Cote, would uphold the original intent and plain text and meaning of Federal Rule of Evidence 702, which governs expert witness testimony/opinions. The U.S. Supreme Court’s landmark 1993 precedent in Daubert v. Merrell Dow Pharms., Inc. created a systematic framework for judges to assess the reliability and relevance of expert witness opinions and exclude pseudoscientific or unreliable expert testimony or opinions, and also underlined the importance of district courts’ gatekeeping role regarding scientific expert testimony. On the other hand, reversing Judge Cote would mean contradicting the Supreme Court, weakening the law, upending more than 30 years of consistent caselaw, opening the courts to floods of junk cases inappropriately attempting to admit junk science, and unfairly tilting the playing field in favor of plaintiffs.
Correspondingly, the 2nd Circuit should focus on Judge Cote’s excluding the plaintiffs’ testimony from their experts, Roberta Ness, M.D., M.P.H. and Andrea Baccarelli, M.D., Ph.D., and certain fragmented selected writings from the defendants’ expert, Stephen Faraone, Ph.D. Of the three, only Dr. Faraone has expertise in ADHD, psychiatry, and neuroscience.
The Supreme Court’s post-Daubert precedent in General Electric v. Joiner (1997) mandates the 2nd Circuit to review Judge Cote’s evidentiary rulings for “abuse of discretion.” It may not reverse unless her rulings were “manifestly erroneous,” meaning a mistake that is clear, obvious, undeniable, and easily recognizable. Because Joiner stated that conclusions and methodologies of expert testimony “are not entirely distinct from one another,” Judge Cote was correct to review them both. The Supreme Court further stated in Kumho Tire Co. v. Carmichael (1999) that the standard “applies as much to the trial court’s decisions about how to determine reliability as to its ultimate conclusion” and that, when analyzing the admissibility of expert witness testimony, “the law grants the trial judge broad latitude” to determine what method is appropriate for evaluating reliability under the circumstances of each case.
Judge Cote correctly found Dr. Ness’ and Dr. Baccarelli’s opinions unreliable on several fronts. She remarked that they “cherry-picked” certain findings while ignoring unsupportive ones, that they also ignored “generally accepted statistical principles,” that their findings were “result-driven,” not “objective or rigorous,” and that their findings were inconsistent with the studies that they cited. Additionally, Judge Cote stated that they intentionally failed to address the “profoundly important issue of confounding by genetics,” even though the measure of how much variation in those traits is due to genetic influence rather than environmental factors was estimated to be 80% for ASD and 74% for ADHD. In fact, Judge Cote noted that Dr. Baccarelli’s previous paper reviewing 46 human studies found an association, but not causation, between acetaminophen and ASD/ADHD, and he wrote that further studies were needed to rule out confounding factors. Furthermore, the record clearly showed that Dr. Ness lacked expertise in ASD/ADHD, was “unable to answer even basic questions about ADHD,” and she acknowledged that she had not even “heard of a relationship between acetaminophen and ADHD” before the plaintiffs retained her. Accordingly, Judge Cote was well within her discretion to exclude those opinions based on their unreliability and similarly flawed methodologies and analyses.
Judge Cote next ruled that the plaintiffs improperly tried to show causation by introducing previous statements by Dr. Faraone that were misleadingly strung together or completely taken out of context, including a PowerPoint slide where he had listed acetaminophen as one of more than a dozen “environmental risk factors” – not causes – for ADHD. Furthermore, Dr. Faraone never stated that maternal prenatal exposure to acetaminophen causes ASD/ADHD in offspring; in fact, he repeatedly stated that there was no reliable scientific evidence of that. Accordingly, Judge Cote was correct to review the entire record and to exclude the plaintiffs’ attempt to introduce their misleading patchwork of Dr. Faraone’s previous writings.
Per Joiner, Judge Cote had the discretion to properly “conclude that there is simply too great an analytical gap between the data and the opinion proffered” to admit the plaintiffs’ experts’ unreliable opinions. The 2nd Circuit should uphold Judge Cote’s evidentiary rulings because FRE 702, Daubert, and over 30 years of caselaw require exclusion of inadequate expert opinions based on flawed or unreliable data, studies, or methodologies, especially where they intentionally ignore or minimize known confounding factors. In fact, the 2nd Circuit previously ruled in Amorgianos v. Amtrak (2002) that all aspects of an expert’s analysis must “be reliable at every step,” which “means that any step that renders the analysis unreliable under the Daubert factors renders the expert’s testimony inadmissible.”
