A federal appeals court on July 13 revived litigation against the maker of Tylenol, ruling that a federal judge went beyond her authority by excluding the testimony of at least three experts called by plaintiffs who say the manufacturer failed to warn them that Tylenol’s active ingredient could cause autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD).
U.S. District Judge Denise Cote exceeded that authority by excluding the testimony of Dr. Andrea Baccarelli, Dr. Eric Hollander, and Brandon Pearson, the panel said, and she may have gone beyond her authority by excluding the testimony of Dr. Roberta Ness.
Cote ruled in 2023 that Baccarelli and other experts offered by plaintiffs cherry-picked and misrepresented the results of studies, and she later dismissed two cases brought by people who say they should have been warned that drugs containing acetaminophen could cause ADHD or ASD.
Appeals court judges said Cote was inconsistent with how she determined experts were or were not reliable.
“Take cherry-picking,” U.S. Circuit Judge Guido Calabresi wrote for the unanimous panel. “Cherry-picking occurs when an expert points to data that support a particular position while ignoring or discrediting data that contradict it. It is not cherry-picking for an expert to prefer one study to another when he offers a coherent, scientifically plausible reason for the preference. This issue is illustrated by the district court’s discussion of Baccarelli’s testimony on genetic confounding (that is, whether any observed association between prenatal acetaminophen and ASD and ADHD can be attributed to genetics).
"No one, including Baccarelli, denies that genetics play a role in ADHD/ASD. But that does not mean that the scientific literature has concluded that genetic confounding accounts for all of the observed association. On this issue, reasonable scientists can, and do, disagree,” he said. “The district court characterized Baccarelli’s reasonable interpretations of studies addressing genetic confounding as cherry-picking. In doing so, the district court ignored the detailed explanations Baccarelli provided for his interpretations. That was error."
The appeals court said that its decision was on the reliability of experts, not on whether acetaminophen causes autism or ADHD.
“Today’s decision from the Second Circuit is a vindication for the scientific evidence our clients have presented from the outset,” Ashley Keller, a lawyer for the plaintiffs, told The Epoch Times in an email. “The Court of Appeals agreed that our experts’ analyses of the voluminous research linking prenatal acetaminophen exposure to neurodevelopmental disorders is reliable. We look forward to presenting that evidence to a jury.”
A spokesperson for Kenvue, Tylenol's maker, told The Epoch Times in an email, that the decision does not suggest a link between Tylenol and autism or ADHD.
“The procedural ruling today does not change the fact that credible, independent science shows no proven link between taking acetaminophen and autism or attention deficit hyperactivity disorder (ADHD),” the spokesperson said.
“Science matters, and we stand with the many public health and medical professionals who have reviewed the science on this topic and agree. We now have another opportunity to show that the plaintiffs’ experts’ opinions are unreliable and should not be allowed. We stand behind the safety of our product and will continue to defend these cases.”
Baccarelli, the dean of the faculty at the Harvard TH Chan School of Public Health, coauthored a review in 2025 that identified what the researchers said was evidence supporting a link between acetaminophen exposure during pregnancy and increased incidence of autism and other neurodevelopmental conditions. Some other studies have concluded there is no association.