Appeals Court Reopens Tylenol Autism Litigation
A US appeals court has revived class-action litigation against Tylenol manufacturer Kenvue, ruling that a lower court improperly excluded key expert witness testimony in cases alleging a link between acetaminophen and autism. The 2nd Circuit US Court of Appeals in New York issued its decision on Monday, allowing plaintiffs to move forward with experts whose testimony was previously dismissed for failing to meet evidentiary standards.
Judicial Reversal on Expert Evidence
The 2nd Circuit panel determined that the US district court erred by excluding three expert witnesses in the ongoing litigation. While the appeals judges did not rule on the scientific validity of the experts’ conclusions, they found the district court failed to properly assess the quality of the testimony before barring it.
The ruling specifically impacts the inclusion of witnesses like Andrea Baccarelli, dean of Harvard University’s public health school. The district court had previously excluded Baccarelli’s testimony, citing a lack of reliable application of scientific methods. Under the new ruling, these witnesses may now participate in the litigation, providing a significant procedural victory for the plaintiffs. The court did, however, uphold the exclusion of two other expert witnesses.
Corporate Defense and Political Pressure
Kenvue, the consumer health company spun out of Johnson & Johnson in 2023, maintains that there is no credible scientific evidence connecting acetaminophen—the active ingredient in Tylenol—to autism or ADHD. In a statement released following the ruling, the company reiterated that independent scientific consensus does not support the plaintiffs’ claims.
The litigation has drawn significant political attention. Last September, Donald Trump suggested that pregnant women should avoid the brand, a claim that prompted a surge in class-action filings. Additionally, Texas Attorney General Ken Paxton initiated a lawsuit against Kenvue in state court, alleging the company failed to warn consumers about potential risks. Paxton’s office has retained the law firm Keller Postman, which also represents plaintiffs in the New York cases.
Market Volatility and Scientific Scrutiny
The medical community has largely challenged the premise of the lawsuits. Research published on June 29 by the American Medical Association (AMA) found no association between paracetamol exposure and an increased risk of autism or ADHD. Despite these findings, the litigation remains a factor for investors.
Shares in Kenvue dipped 1 per cent following the announcement of the court’s decision, while shares of Kimberly-Clark—which announced a $49 billion acquisition of Kenvue in November—dropped 2 per cent. According to a research report from BNP Paribas, the ongoing political and legal pressure has contributed to a decline in Tylenol’s market share, which currently sits below 20 per cent of the over-the-counter pain relief category.
The Path Back to Trial
As the case returns to the district court level, the focus shifts to whether the plaintiffs can successfully present their evidence before a jury. Ashley Keller, a partner at Keller Postman, described the appeals court’s decision as a vindication of the scientific evidence presented by the plaintiffs. The litigation is expected to continue throughout the year as the acquisition process between Kenvue and Kimberly-Clark moves toward completion.
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