On July 13, 2026, the U.S. Court of Appeals for the Second Circuit issued a unanimous 64-page decision in Rutledge v. Walgreen Co. and Phippen v. Walgreen Co., vacating U.S. District Judge Denise Cote's 2023 summary judgment order and resurrecting approximately 550 federal lawsuits against Kenvue Inc., the Johnson and Johnson consumer spin-off, along with major retail defendants including Walmart, CVS, and Walgreens.
Authored by Circuit Judge Guido Calabresi, the panel held that the district court exceeded its gatekeeping authority under Federal Rule of Evidence 702 when it excluded plaintiffs' primary general causation experts, and struck down the defense's impossibility preemption argument.
The battleground has shifted from general causation admissibility to specific causation, and dockets built on unverified claims face steep attrition while firms enforcing strict intake criteria stand to capture significant settlement leverage.
What the Second Circuit held
The panel issued two distinct holdings that reshape MDL 3043:
- On FRE 702 gatekeeping, Judge Calabresi emphasized that a trial court must ensure expert methodology is reliable rather than adjudicate whether an expert's ultimate conclusions are correct. The court rejected Judge Cote's finding that grouping ASD and ADHD under a broad neurodevelopmental umbrella constituted junk science, noting that regulatory bodies including the FDA routinely employ transdiagnostic frameworks. Disagreements over diagnostic endpoints go to the weight of evidence for a jury, not admissibility.
- On preemption, defendants argued that federal OTC labeling regulations under 21 C.F.R. § 201.63 made it impossible for manufacturers to add state-mandated ASD and ADHD warnings. The Second Circuit adopted a strict textual reading: while that regulation sets a mandatory baseline, nothing in its text expressly prohibits manufacturers from adding supplemental specific risk warnings, meaning federal OTC labeling regulations do not provide blanket immunity against state failure-to-warn claims.
The expert matrix after the appellate ruling
Three plaintiff experts were reinstated, and two exclusions were affirmed:
- Dr. Andrea Baccarelli (Harvard Chan, epidemiologist): Reinstated. Bradford Hill analysis and transdiagnostic grouping fall within sound methodology.
- Dr. Eric Hollander (Albert Einstein, psychiatrist): Reinstated. Clinical mechanisms and biological plausibility hold a reliable foundation.
- Dr. Brandon Pearson (Columbia University, toxicologist): Reinstated. Toxicological neural architecture analysis found sound.
- Dr. Robert Cabrera (toxicologist/teratologist): Excluded, affirmed. Used Bradford Hill as a mechanistic checklist not as a weight-of-evidence framework.
- Dr. Stan Louie (pharmacologist): Excluded, affirmed. Failed to bridge the 28-day analytical gap between exposure timing and neurodevelopmental windows.
The dueling scientific paradigms
The Second Circuit stated its ruling is not a declaration that acetaminophen causes ASD or ADHD, but that the scientific debate belongs before a jury. Two opposing epidemiological frameworks will define that fight.
The plaintiff paradigm centers on the Johns Hopkins cord blood study published in JAMA Psychiatry in 2019, which analyzed objective cord blood biomarkers across 996 subjects. Subjects in the top tertile of acetaminophen exposure showed an odds ratio of 3.62 for ASD and 2.86 for ADHD. The Mount Sinai Navigator Guide published in BMC Environmental Health in 2025 reviewed 46 studies and identified 27 positive links between prenatal acetaminophen exposure and neurodevelopmental outcomes.
Central to the defense is a 2024 Swedish study published in JAMA that used a sibling-control design and pulled from a 2.5 million child cohort spanning 1995 to 2019. Using a sibling-control approach to rule out genetic factors, the hazard ratio came out to 0.98, essentially a null result. The defense also points to unified support from ACOG, SMFM, and AAP, who caution that untreated maternal fever is the real risk factor here.
Each paradigm carries a vulnerability. Cord blood only proves exposure at delivery given the drug's 2.5-hour half-life, providing no direct proof of exposure during the first or second trimester neurodevelopmental windows. The Swedish study relies on maternal self-report for OTC drug use, which carries inherent underreporting risks compared to the objective biomarkers used in the Johns Hopkins cohort.
Corporate knowledge and Project Cocoon
Internal J&J communications from 2018 show that Rachel Weinstein, U.S. Director of Epidemiology for J&J's Janssen division, evaluated emerging observational studies and noted that the weight of evidence was starting to feel heavy. The toxicological mechanism involves acetaminophen crossing the placental barrier, where fetal brain expression of the CYP2E1 enzyme generates NAPQI, a reactive oxidative metabolite that depletes glutathione and drives neurite arborization disruption and epigenetic alterations supporting punitive damages arguments.
The Texas Attorney General filed suit under the Texas Deceptive Trade Practices Act alleging Johnson and Johnson deliberately spun off its consumer division into Kenvue under an internal initiative code-named Project Cocoon specifically to shield primary corporate assets from impending acetaminophen mass tort liabilities.
The political development reshaping the jury pool
In September 2025, Executive Branch leadership held a White House briefing asserting that prenatal acetaminophen is a very big factor in causing autism, citing the Mount Sinai review co-authored by Dr. Baccarelli, with the FDA concurrently signaling impending labeling updates. Plaintiff counsel leveraged this at the appellate level, successfully arguing that the Judicial Branch could not declare research junk science under FRE 702 when the Executive Branch was relying on that exact same research to establish national public health policy. The briefing also reshaped the prospective jury pool in ways that favor plaintiff narratives heading into bellwether selection.
Intake criteria that survive specific causation challenges
With cases remanded to Judge Cote in the Southern District of New York, defense teams will target maternal age, genetics, and confounding indications including maternal fever. Two non-negotiable intake filters define which inventory survives:
To verify exposure objectively, you need contemporaneous OB-GYN notes that recommend Tylenol by name, pharmacy purchase records, or archived cord blood documentation. Claims based only on retrospective maternal memory tend to get dismissed early on specific causation grounds.
The severity of the diagnosis requires Level 3 ASD with significant impairment of functioning as documented in IEPs, 504 Plans and ABA therapy evaluations submitted prior to litigation. Lower-severity, broad diagnoses face the greatest risk of attrition against the null result from the Swedish sibling study.
Atraxia Media builds MDL 3043 inventory around strict causation criteria
The Second Circuit ruling restored the general causation foundation Judge Cote eliminated in 2023, but the firms that benefit most will be those whose inventory was built around contemporaneous exposure records and high-severity diagnoses from the first signed retainer. Atraxia Media structures acquisition pipelines around the specific intake criteria that define viable MDL 3043 claims and separate them from the broad unverified inventory facing steep attrition on remand. Contact Atraxia Media today to discuss how we can help your firm build an acetaminophen docket positioned for the specific causation phase ahead.