The high-stakes litigation over Tylenol and its alleged connection to autism is gaining renewed momentum. Plaintiffs in more than 500 lawsuits that were previously dismissed are urging the 2nd U.S. Circuit Court of Appeals to consider a newly issued health warning from the Trump administration advising pregnant women to avoid acetaminophen — the active ingredient in Tylenol.
The plaintiffs’ attorneys argue that the government’s stance lends significant credibility to the expert opinions they presented in court and should weigh heavily as the appellate court decides whether to revive the lawsuits.
Plaintiffs Argue “Separation of Powers” Is at Stake
In a letter filed Wednesday, plaintiffs’ counsel Ashley Keller urged the court to recognize the gravity of the administration’s announcement. The Trump administration, led by FDA Commissioner Marty Makary and Health Secretary Robert F. Kennedy Jr., held a White House press briefing earlier this week warning pregnant women against acetaminophen use.
Keller told the appeals court that ignoring the administration’s position would raise “grave separation of powers concerns.” He argued that the government’s reliance on several of the same experts that plaintiffs had called — including Dr. Andrea Baccarelli, dean of Harvard’s T.H. Chan School of Public Health — validates the scientific basis of their claims.
“Where the executive branch is making public health recommendations based on this very science, the judiciary should not disregard it,” Keller wrote.
Judge Previously Dismissed 500+ Lawsuits
The lawsuits, consolidated before U.S. District Judge Denise Cote in Manhattan, alleged that prenatal exposure to acetaminophen caused autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) in children.
Judge Cote dismissed the claims in 2024, finding that the plaintiffs’ expert testimony was not sufficiently reliable. She wrote that the plaintiffs’ scientists had engaged in a “results-driven analysis” and “cherry-picked data” rather than applying generally accepted methodologies for determining causation.
Under federal product liability law, plaintiffs bear the burden of proving general causation — that a product is capable of causing the alleged harm — through admissible expert testimony. Without this foundation, individual claims cannot proceed to trial.
Kenvue, the Maker of Tylenol, Pushes Back
Lawyers for Kenvue Inc., the Johnson & Johnson spinoff that now owns Tylenol, strongly opposed Keller’s request.
In their filing, Kenvue’s lead counsel Jay Lefkowitz noted that even as the FDA urged caution, it explicitly stated that a causal link between acetaminophen use and autism “has not been established.” He also emphasized that Dr. Baccarelli himself has publicly acknowledged that more research is needed to confirm any connection.
“There is thus no conflict between the government’s action and the district court’s opinion,” Lefkowitz wrote. “The government’s statements do not transform unreliable expert opinions into admissible evidence.”
Kenvue expressed confidence that the appeals court will affirm Judge Cote’s ruling, stressing that decades of scientific study have not conclusively linked acetaminophen to autism or ADHD.
Hearing Rescheduled as Stakes Rise
The 2nd Circuit had originally scheduled oral arguments for October 6, but the court recently postponed the hearing to November, giving both sides time to submit supplemental briefing.
Legal scholars say it is unusual for courts to rely heavily on presidential announcements when evaluating scientific evidence in litigation. “It’s not as if there’s been a new peer-reviewed study changing the scientific consensus,” said Elizabeth Chamblee Burch, a professor at the University of Georgia School of Law. “Judges generally look for reliable methodologies and reproducible results — not political statements.”
Broader Implications for Mass Tort Litigation
The outcome of this appeal could have far-reaching implications for product liability and mass tort litigation nationwide. If the plaintiffs succeed in reviving their claims by pointing to government advisories, it could open the door for similar arguments in other high-profile cases involving consumer products and pharmaceuticals.
Legal experts warn that this could lower the threshold for plaintiffs to survive early challenges to their cases, potentially leading to more jury trials based on precautionary government statements rather than conclusive scientific evidence.
At the same time, public health advocates say the Trump administration’s advisory reflects a precautionary principle designed to protect vulnerable populations, and courts should not ignore it. “We’re talking about the health of pregnant women and unborn children,” said one advocacy group spokesperson. “Even if the science is still emerging, the risk-benefit calculation favors caution.”
What Comes Next
As the November hearing approaches, both sides are preparing to frame their arguments not just around science, but also around the role of courts in responding to government health advisories.
For now, the litigation remains one of the most closely watched mass tort cases in the country, drawing attention from scientists, public health agencies, and pharmaceutical companies. A decision to revive the lawsuits could reopen the door for hundreds of families seeking compensation — and force Kenvue to defend its flagship product before a jury.
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