A unanimous three-judge panel of the Second Circuit Court of Appeals on Monday, July 13, reversed the district court's exclusion of three plaintiff general causation experts in In re: Acetaminophen – ASD-ADHD Products Liability Litigation (MDL No. 3043), reviving more than 500 lawsuits that had been dismissed after the December 2024 Daubert ruling. The cases now return to Judge Denise Cote in the Southern District of New York. For plaintiff firms, the headline is simple: as of Monday morning, Tylenol is an active federal tort again.
What Happened
Writing for the panel in a 64-page opinion, Judge Guido Calabresi held that the district court exceeded its gatekeeping role by weighing competing scientific conclusions instead of assessing whether the experts applied reliable, accepted methodologies. The panel found the excluded experts had offered defensible readings of a body of evidence on which qualified scientists genuinely disagree.
The reinstated experts are Dr. Andrea Baccarelli, Dean of the Harvard T.H. Chan School of Public Health; Dr. Eric Hollander of the Albert Einstein College of Medicine; and Dr. Brandon Pearson, a toxicologist at Columbia University. The panel affirmed the exclusion of two other plaintiff experts and declined to rule on a sixth expert offered in a companion ADHD-only case.
The defendants include Kenvue — the Tylenol maker spun off from Johnson & Johnson in 2023 and now being acquired by Kimberly-Clark — along with major retailers that sell store-brand acetaminophen. Kenvue responded that the ruling is procedural, does not establish any causal link, and that it intends to challenge the reliability of the plaintiffs' experts again on remand.
What the Court Did Not Decide
The panel was explicit that it was not deciding whether acetaminophen causes autism or ADHD, and was not deciding whether manufacturers must warn about any alleged risk. This is an admissibility ruling: juries will now be permitted to hear and weigh the reinstated testimony. No settlements exist in this litigation, and no verdict values can responsibly be projected. Marketing that implies a proven causal link or a settled outcome creates bar-compliance risk.
Why It Matters for Plaintiff Firms
Tylenol was one of the most heavily advertised mass torts of 2022–2023 before the docket collapsed. The revival restores that market with two things it lacked the first time: a unanimous appellate opinion validating the plaintiffs' expert methodology, and an FDA labeling process on pregnancy-related acetaminophen language that began in late 2025. The ruling covers both autism spectrum disorder and ADHD claims, though the two tiers carry very different case values and screening requirements. Firms weighing re-entry should also weigh the risks: remand means renewed Rule 702 challenges, two of five experts remain excluded, and a well-funded defendant has every incentive to keep fighting.
What's Next
The revived cases return to Judge Cote for further proceedings, where Kenvue has said it will renew its challenges to the plaintiffs' experts. The advertising auction for Tylenol cases is re-forming now, and acquisition costs will move as firms re-enter the market. For a full breakdown of case criteria, ASD versus ADHD screening tiers, historical acquisition benchmarks, and compliant claims language, see our analysis: The Tylenol MDL Is Back: What the Second Circuit's July 13 Ruling Means for Plaintiff Firms.