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For families who filed Tylenol autism lawsuits after their children were diagnosed with autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD) following prenatal exposure to acetaminophen, the active ingredient in Tylenol, the Second Circuit has just handed them an important legal victory. On July 13, 2026, the U.S. Court of Appeals for the Second Circuit ruled that a federal lower court had wrongly shut down these cases by excluding the families' medical experts from testifying. The decision breathes new life into litigation that had appeared to be stalling.
Thousands of families who believe their children's neurodevelopmental conditions were caused by prenatal acetaminophen use previously had their cases consolidated into federal multidistrict litigation (MDL) in the Southern District of New York. In 2023, the MDL effectively came to a halt when U.S. District Judge Denise Cote excluded the plaintiffs' expert witnesses, concluding that their analyses improperly relied on cherry-picked and misrepresented study results. Without those experts, the families had no way to present scientific evidence in support of their claims, and the cases lost their momentum. But the Second Circuit's July 2026 ruling reverses that outcome.
Court Accepts Dr. Baccarelli’s Methodology
In complex personal injury cases involving science and medicine, expert witnesses play a necessary role. They translate technical research and data into testimony that a jury can evaluate. Federal courts act as gatekeepers, with judges having the authority to decide whether a proposed expert's methods and reasoning meet a sufficient standard of reliability before they can testify. The central question in this case was whether the plaintiffs' experts cleared that bar.
The Second Circuit concluded that they did, and that the lower court went too far in excluding them. The appeals panel took particular issue with how the lower court evaluated the methodology of Dr. Andrea Baccarelli, dean of the Harvard T.H. Chan School of Public Health. Baccarelli used a framework called the Bradford Hill criteria, which is a widely accepted set of factors that scientists use to assess whether an observed association between two things may reflect a cause-and-effect relationship. The lower court rejected his approach, but the Second Circuit said that rejection was an error. "That ruling was erroneous because it penalized Baccarelli for using a methodology that epidemiologists routinely use," the panel wrote.
The appeals court also rejected the conclusion that Baccarelli had cherry-picked data, explaining that it is not cherry-picking for an expert to favor one study over another when a scientifically sound reason is given for that preference. Two additional expert witnesses, including psychiatrist Eric Hollander and toxicologist Brandon Pearson, were also found to have been wrongly excluded. As the panel put it, these were "concededly qualified experts" whose opinions "comport with methodologies applied by other scientists in their fields, and constitute acceptable interpretations of scientific evidence."
What Does the Latest Ruling Decide?
The Second Circuit was careful to clarify that its decision concerns the rules of evidence, specifically, whether these expert witnesses should have been allowed to testify. It is not a finding that acetaminophen causes autism or ADHD, and it is not a ruling on the merits of any individual family's claim. "We are also not deciding whether the manufacturers of acetaminophen must warn consumers about any alleged risk posed by such a potential causal relationship," the panel wrote.
What it does mean is that these cases can now move forward with the scientific evidence that affected families have long sought to present. Ashley C. Keller, counsel for the families, described the decision as "a vindication for the scientific evidence our clients have presented from the outset."
Think You Have a Tylenol Lawsuit Case? Bring It to Us.
If your child was diagnosed with autism spectrum disorder or ADHD and you used Tylenol or another acetaminophen product during pregnancy, the Second Circuit's ruling may be significant to your situation. At Kershaw Talley Barlow, we accept Tylenol lawsuit cases on behalf of families throughout California and across the country, and we have been following the legal developments surrounding this situation closely. Bring your case to our desk, and let us put our insight, resources, and experience to use for you and your family.
For more information, call us at (916) 520-6639 and get a free consultation with our Tylenol autism lawsuit attorneys.
