The 2nd Circuit reversed a pretrial dismissal and ordered that parents suing over prenatal Tylenol exposure get to present expert witnesses to juries, finding a district judge improperly excluded testimony by weighing scientific disputes rather than policing methodology.
A unanimous three-judge panel of the 2nd U.S. Circuit Court of Appeals has undone a lower court’s dismissal of hundreds of lawsuits brought by parents who say their children developed autism or ADHD after prenatal exposure to acetaminophen. The panel concluded that U.S. District Judge Denise Cote went beyond the judge’s gatekeeping role by effectively judging the science instead of assessing whether the experts used reliable methods. That ruling restores key expert testimony and sends the cases back for further proceedings.
The appeals court specifically rejected Judge Cote’s decision to exclude testimony from three plaintiffs’ experts and said the right question is whether experts used sound, generally accepted methodologies. The court did not rule on causation or declare the drug dangerous; it focused on the admissibility standard under the rules of evidence. In plain terms, the judges insisted on procedure: let juries weigh competing scientific claims when methods are defensible.
The panel wrote an important caveat in its opinion and made clear the limits of its move back to the courtroom:
“These appeals concern what qualifies as admissible epidemiological testimony in support of a general causal relationship. We are not deciding whether there is a general causal relationship between acetaminophen and ADHD and/or ASD. We are also not deciding whether the manufacturers of acetaminophen must warn consumers about any alleged risk posed by such a potential causal relationship.”
That distinction matters because the court refused to short-circuit the litigation based on its own view of contested science. Instead of barring the evidence outright, the appellate judges gave the families the procedural chance to present experts and let juries evaluate credibility. This is a pushback against judicial overreach that substituted final judgment for a factfinder’s role.
The appeal reinstated testimony from Andrea Baccarelli, dean of the Harvard T.H. Chan School of Public Health; Eric Hollander, a psychiatry professor at Albert Einstein College of Medicine; and Brandon Pearson, a toxicologist at Columbia University. Each had been excluded by Cote’s December 2024 order after she described their work as unreliable. The appeals court said the question for trial judges is method, not whether one side’s conclusions are correct.
Judge Cote’s opinion used unusually sharp language, accusing one expert of “cherry-picked and misrepresented study results,” which effectively ended the litigation before a jury could hear from witnesses. The appellate judges rejected that approach, noting that reasonable scientists disagree and that courts routinely manage disputes between qualified experts. By stepping into that scientific debate, the district court crossed the line from gatekeeping into fact-finding.
Baccarelli had testified that “substantial evidence” supports a causal relationship between frequent, high-dose acetaminophen use during pregnancy and neurodevelopmental disorders in children. The appeals court emphasized that excluding his testimony on the basis of conclusion rather than methodology was improper. Republican legal commentators will see this as a defense of the jury system and a rebuke of activist judging that short-circuits public accountability.
The underlying science remains disputed. Some observational studies report a small association between prenatal acetaminophen use and neurodevelopmental issues, while larger work that controlled for genetic and other confounders has found no evidence of a causal link. That fractured record is exactly why juries, not lone judges, should get the chance to hear competing expert views and assess credibility and context.
The medical establishment has pushed back on claims that acetaminophen poses a pregnancy risk. Dr. Steven Fleischman, president of the American College of Obstetricians and Gynecologists, warned that such claims are “not only highly concerning to clinicians but also irresponsible when considering the harmful and confusing message they send to pregnant patients, including those who may need to rely on this beneficial medicine during pregnancy.” He also said such suggestions “dangerously simplify the many and complex causes of neurologic challenges in children.”
Institutional alarm does not remove the need for courts to adjudicate contested claims when qualified experts disagree. The appeals court made clear that deference to professional organizations cannot substitute for the adversarial testing of evidence. This ruling reasserts a basic principle: judges should police methods, juries should weigh the rest.
The legal fight acquired unusual political attention when President Donald Trump urged pregnant women in September to avoid acetaminophen, saying, “Don’t take Tylenol. Don’t take it. If you just can’t, I mean, fight like h*** not to take it.” HHS Secretary Robert F. Kennedy Jr. echoed that caution, and their comments drew criticism from medical groups. Still, the executive branch attention underscored how unsettled the issue felt outside courtroom walls.
Hundreds of families now have their claims restored and will press forward with litigation against acetaminophen manufacturers, whose corporate names were not singled out in the opinion. The appeals court did not specify whether the suits will proceed individually or as consolidated multidistrict litigation, and it left open how trial judges should apply the evidentiary standard in practice. Those procedural questions are likely to produce fresh legal skirmishing.
What the ruling does do is put the disputes where they belong: in open court with live testimony and adversarial testing. Parents who contend a common over-the-counter drug injured their children will now get their day before juries, and manufacturers will have to defend their products under cross-examination. That restoration of process will let communities, through juries, sort out hard scientific claims rather than letting a single judge shut the door.
