Second Circuit Gets It Wrong on Rule 702, Reviving Hundreds of Junk Science Tylenol Suits
A federal appeals court handed the plaintiffs’ bar a major victory— and handed American consumers and the civil justice system a significant setback. On July 13, the U.S. Court of Appeals for the Second Circuit reversed U.S. District Judge Denise Cote’s well-reasoned decision to exclude plaintiffs’ expert witnesses in the acetaminophen multidistrict litigation, reviving more than 500 lawsuits alleging that prenatal Tylenol use causes autism and ADHD in children.
What Judge Cote Got Right
After a rigorous review of the scientific record, Judge Cote excluded all three plaintiffs’ causation experts under Federal Rule of Evidence 702, applying the newly amended rule intended to strengthen judges’ gatekeeping role. The 2023 amendments made clear that courts must find expert testimony is supported by sufficient facts and reliably applied — not merely that a credentialed witness is willing to say so. Judge Cote took that responsibility seriously. She examined the studies underlying each expert’s opinions, weighed the methodological choices, and concluded that the experts had cherry-picked studies and failed to demonstrate that their conclusions rested on generally accepted science.
What the Second Circuit Got Wrong
The Second Circuit panel, in an opinion authored by Circuit Judge Guido Calabresi, concluded that Judge Cote had “overstepped” by resolving disputed scientific questions that — in the panel’s view — should go to a jury. The court found that the excluded experts’ opinions “constitute acceptable interpretations of scientific evidence where scientists may, and in fact do, disagree.”
But that is precisely the problem. Rule 702 exists so that scientific disputes that have not been resolved through rigorous, peer-accepted methodology do not become fodder for lay juries awarding massive verdicts. The gatekeeping function is not a rubber stamp. When a judge carefully analyzes whether an expert’s methodology is reliable and concludes it falls short, that is the system working as designed — not an overstep.
The panel even felt compelled to state explicitly that it was “not deciding whether there is a general causal relationship between acetaminophen and ADHD and/or ASD” and was “certainly not deciding the approach that policymakers concerned with protecting public health should take.” That disclaimer underscores the problem: the Second Circuit acknowledged it was not making a scientific determination, yet it opened the courthouse door anyway.
What do the Real Experts Say?
Acetaminophen is one of the most widely used pain relievers in the world. It is recommended by the American College of Obstetricians and Gynecologists as the safest over-the-counter pain option during pregnancy. The FDA has not changed its guidance on the drug and no major scientific or regulatory body has concluded that prenatal acetaminophen use causes autism.
