A federal appeals court on Monday revived hundreds of lawsuits alleging that acetaminophen use during pregnancy causes autism and ADHD in children, ruling that a lower court improperly threw out testimony from scientific experts. The unanimous decision from the 2nd U.S. Circuit Court of Appeals hands a major victory to families who say the maker of Tylenol and major pharmacy chains failed to warn them about the risks.
The 64-page ruling, authored by Circuit Judge Guido Calabresi, a Clinton appointee, found that the experts whose testimony was excluded were qualified and that their conclusions fell within the bounds of legitimate scientific disagreement. The decision sends the cases back for further proceedings and puts defendants, including Kenvue, the manufacturer of Tylenol, along with Walgreens, CVS, Walmart, and Target, squarely back in the legal crosshairs.
For years, families raising children with autism and ADHD have pressed these claims, and for years, the pharmaceutical and retail establishment has pushed back. Monday's ruling does not settle the underlying science. But it does say those families deserve their day in court, and that a judge was wrong to shut the door on them.
The core of the ruling is procedural, not scientific. The 2nd Circuit found that the lower court overstepped when it excluded expert testimony that supported a causal link between prenatal acetaminophen exposure and neurodevelopmental disorders. Calabresi wrote that the experts were "concededly qualified" and that their work met recognized standards in their fields.
As The Hill reported, Calabresi stated in the opinion:
"Those concededly qualified experts offered opinions that comport with methodologies applied by other scientists in their fields, and constitute acceptable interpretations of scientific evidence where scientists may, and in fact do, disagree on the ultimate answer to the causal question that they are assessing."
Calabresi also noted that the ruling on expert testimony had no bearing on whether a link between acetaminophen and autism or ADHD actually exists. That question, the court made clear, is for a jury to weigh, not for a judge to resolve by excluding the evidence before trial.
The Washington Examiner reported that the appeals court unanimously overturned a December 2024 dismissal by District Judge Denise Cote, and reinstated testimony from three prominent experts, including the dean of the Harvard T.H. Chan School of Public Health. The lower court, in the Examiner's account, was found to have overstepped its role by functioning as a gatekeeper of scientific conclusions rather than evaluating whether the expert methodology was sound.
That distinction matters. Federal rules on expert testimony, governed by the Supreme Court's Daubert standard, require judges to evaluate methodology, not to pick winners in scientific debates. The 2nd Circuit found that Judge Cote crossed that line.
Newsmax reported that more than 500 lawsuits were consolidated in the litigation, with plaintiffs alleging that prenatal Tylenol exposure caused their children's autism or ADHD. Two of the three judges on the 2nd Circuit panel had previously questioned whether the original dismissal was premature, with one suggesting the cases may have been appropriate for a jury all along.
The legal pressure is not limited to federal court. Texas Attorney General Ken Paxton sued Tylenol manufacturers Johnson & Johnson and Kenvue, alleging deceptive marketing to pregnant women. That state-level action adds another front to a fight that now spans multiple jurisdictions.
The pharmaceutical industry has long treated these lawsuits as nuisance claims built on shaky science. Monday's ruling makes that posture harder to maintain. A federal appellate court, unanimously, has now said the science is contested enough that it belongs before a jury, not in a judge's wastebasket.
Kenvue, the Johnson & Johnson spinoff that manufactures Tylenol, issued a statement Monday insisting the ruling changes nothing about the underlying evidence. The company said:
"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). Science matters, and we stand with the many public health and medical professionals who have reviewed the science on this topic and agree."
A Kenvue spokesperson added that the company sees "another opportunity to show that the plaintiffs' experts' opinions are unreliable and should not be allowed," and said Kenvue is "exploring all options regarding this decision."
Kenvue shares fell 1.35 percent by Monday evening. The market's reaction was modest, but the legal exposure is not. Hundreds of individual cases now move forward, each with its own set of facts, damages claims, and potential jury verdicts. For a company that has staked its defense on keeping these cases out of court entirely, the appeals ruling is a significant setback.
The American College of Obstetricians and Gynecologists has repeatedly denied a link between neurodevelopmental disorders and prenatal acetaminophen use. Dr. Steven Fleischman of the organization has called suggestions of such a link "not only highly concerning to clinicians but also irresponsible when considering the harmful and confusing message they send to pregnant patients."
The court ruling arrives against a backdrop of growing federal attention to the issue. Last year, President Trump and HHS Secretary Robert F. Kennedy Jr. warned pregnant women not to take acetaminophen. Kennedy stated that the FDA "would begin updating the label on acetaminophen" and would begin notifying physicians that Tylenol "can be associated with a very increased risk of autism."
Trump himself was direct. "Don't take Tylenol. Don't take it. If you just can't, I mean, fight like h*** not to take it," he said, as the Washington Examiner reported.
That warning drew sharp criticism from medical organizations and from Democrats who accused the administration of fearmongering. But the 2nd Circuit's ruling now lends procedural weight to the very concerns the administration raised. Whether the science ultimately supports a causal link is an open question. What is no longer open is whether families can present their case to a jury.
The broader pattern of federal agencies facing scrutiny over drug safety and labeling decisions is not new. The FDA has seen significant leadership turnover in recent years, with senior officials departing or being fired amid disputes over regulatory direction. Questions about how aggressively the agency polices pharmaceutical marketing, and how honestly it communicates risk, cut across multiple drug categories.
The acetaminophen litigation fits a broader trend of federal courts stepping in where regulators and industry have resisted accountability. When judges exclude expert testimony wholesale, they effectively decide scientific disputes by fiat, removing the question from the adversarial process that the legal system is designed to provide.
The 2nd Circuit's rebuke of that approach echoes tensions seen in other high-profile pharmaceutical and regulatory battles. Courts have increasingly been asked to referee disputes over drug access, labeling, and safety, from Supreme Court rulings on pharmaceutical availability to circuit-level fights over dispensing rules and regulatory authority.
In each case, the core question is the same: who decides? A judge sitting alone, an agency captured by industry relationships, or a jury of citizens weighing the evidence? The 2nd Circuit's answer in the acetaminophen cases is clear. The evidence goes to the jury.
That answer should worry Kenvue and the pharmacy defendants. Juries are unpredictable. And when parents sit across the courtroom from a Fortune 500 company, telling a jury their child was harmed by a product they were told was safe, the dynamics shift in ways that no corporate press release can control.
Several important questions remain open. The FDA label update Kennedy announced has not been confirmed as completed. The total number of lawsuits, described as "hundreds", lacks a precise public count. And the specific instructions the 2nd Circuit issued to the lower court on remand are not yet clear from public reporting.
The scientific debate itself is far from settled. Some studies have found associations between prenatal acetaminophen exposure and neurodevelopmental outcomes. Others have found none. Kenvue and the medical establishment point to the latter. Plaintiffs' experts point to the former. The 2nd Circuit said both sides deserve to make their case.
The growing willingness of federal appellate courts to check lower-court gatekeeping on scientific evidence is a development worth watching. It reflects a judiciary increasingly skeptical of judges who substitute their own scientific conclusions for the adversarial process.
For the families at the center of these cases, Monday's ruling is not vindication. It is simply access, the chance to present their evidence, call their experts, and ask a jury to weigh the facts. That chance was taken from them. Now it has been restored.
When hundreds of families say a product harmed their children, and qualified scientists say the data supports a link, the least the legal system can do is let them make their case. A lower court said no. The 2nd Circuit, unanimously, said yes. The rest belongs to a legal system that works best when it trusts juries with hard questions instead of hiding behind procedural shortcuts.
Accountability starts with access to the courtroom. These families finally have it again.