A unanimous panel of the 2nd U.S. Circuit Court of Appeals overturned a lower court's dismissal of hundreds of lawsuits filed by parents who say their children developed autism or ADHD after prenatal exposure to Tylenol, ruling that a federal judge overstepped by throwing out key expert testimony.

The Tuesday decision reverses a December 2024 ruling by U.S. District Judge Denise Cote, a Bill Clinton appointee, who had concluded that the plaintiffs' expert witnesses relied on unreliable science. The appeals court found Cote "exceeded its role by weighing competing scientific conclusions rather than determining whether the experts used reliable, generally accepted methodologies."

In plain terms: the trial judge played scientist instead of gatekeeper. The three-judge appellate panel, all Democratic appointees, said that was wrong, and now the families get another chance to make their case.

What the ruling says, and what it doesn't

The appeals court was careful to draw boundaries around its own decision. The panel wrote:

"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. The court did not declare Tylenol dangerous. It said the families deserve the chance to present their evidence to a jury, and that Judge Cote was wrong to block that path.

The ruling reinstated testimony from three plaintiffs' experts: 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. All three had been excluded by Cote's 2024 order.

The lower court's reasoning, and its limits

Judge Cote had gone further than simply questioning the experts' conclusions. She wrote that Baccarelli, the Harvard dean, had "cherry-picked and misrepresented study results" and was therefore unreliable. That language is sharp for a judicial opinion, and it effectively ended the litigation before any jury heard a word of testimony.

Baccarelli had previously testified that "substantial evidence" supports a causal relationship between frequent, high-dose acetaminophen use during pregnancy and neurodevelopmental disorders in children. The appeals court found that the proper question was not whether his conclusions were right, but whether his methodology met the standard for admissibility under the rules of evidence.

During oral arguments before the appellate panel, Judge Gerard Lynch observed that "reasonable scientists do appear to disagree", suggesting that live scientific debate should not automatically disqualify expert testimony from reaching a courtroom.

That observation cuts to the heart of the matter. Courts routinely handle disputes where qualified experts land on opposite sides. The jury's job is to weigh credibility. The judge's job is to ensure the methodology is sound. Cote, the appeals court concluded, confused the two roles.

The science remains contested

The underlying scientific question is far from settled. Some observational studies have found "a small association" between prenatal acetaminophen use and neurodevelopmental disorders. Larger studies that accounted for genetic and other confounding factors found "no evidence" that the medication causes autism or ADHD.

That split is precisely why the case is so difficult, and why it belongs in front of a jury, not buried under a pretrial ruling. When credentialed researchers at Harvard, Columbia, and Albert Einstein disagree with other credentialed researchers, the courtroom is supposed to be the place where competing claims get tested, not suppressed.

The medical establishment has pushed back hard on any suggestion that Tylenol poses a risk during pregnancy. Dr. Steven Fleischman, president of the American College of Obstetricians and Gynecologists, said in response to broader public discussion of the issue:

"Suggestions that acetaminophen use in pregnancy causes autism 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."

Fleischman also said such suggestions "dangerously simplify the many and complex causes of neurologic challenges in children." Those are strong words from a major medical organization, and they reflect the intensity of the debate.

But intensity of opposition does not equal resolution. Courts exist to test claims, not to defer to institutional opinion when qualified experts disagree. Pregnancy-related health policy has become an increasingly active area for both courts and legislatures, as seen in Oklahoma's recent law making it a felony to traffic abortion pills into the state.

Trump and Kennedy weighed in first

The legal fight over Tylenol and pregnancy has an unusual political backdrop. In September, President Donald Trump urged pregnant women to avoid the drug.

"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. joined Trump in urging pregnant women to avoid Tylenol whenever possible. The comments drew sharp criticism from medical groups, including ACOG, but they also signaled that the administration takes the potential risk seriously, well before the appeals court weighed in.

The federal judiciary and the executive branch rarely align this closely on a contested health question. The appeals court's ruling does not endorse Trump's position, but it does validate the premise that the science is unsettled enough to warrant a full hearing.

Reproductive health decisions, from medication access to safety warnings, have drawn increasing judicial scrutiny in recent years. The Supreme Court's intervention on abortion pill access and the Fifth Circuit's halt of mail-order abortion pills reflect a broader pattern of courts stepping into contested questions about what pregnant women are told, and sold, by the medical system.

What comes next

The appeals court's ruling sends the cases back for further proceedings. Hundreds of families now have their claims restored. The acetaminophen manufacturers, whose specific corporate names were not identified in the ruling, will face renewed pressure to defend their product in open court rather than behind a pretrial dismissal.

Several questions remain unanswered. The precise number of lawsuits revived is described only as "hundreds." Whether the cases proceed as consolidated multidistrict litigation or as individual suits is not specified. And the specific evidentiary standard the appeals court expects trial judges to apply going forward will likely generate its own round of legal argument.

What is clear is that the families who filed these suits, parents of children with autism and ADHD who believe a widely used over-the-counter drug played a role, will finally get the chance to present their evidence. Judge Cote decided the science wasn't good enough for a courtroom. Three appellate judges, unanimously, said she was wrong to make that call.

The question now is whether a jury, given all the evidence, agrees with the parents or the manufacturers. That's how the system is supposed to work, and it took an appeal to make it happen.

When a federal judge decides to play gatekeeper to scientific debate rather than let a jury hear both sides, families pay the price. The appeals court got this one right: let the evidence in, and let the people decide.