The Second Circuit's ruling in Rutledge v. Walgreen Co. redraws the boundary between judicial gatekeeping and jury decision-making, with significant consequences for how companies and litigants approach complex causation disputes.

In Rutledge v. Walgreen Co., 182 F.4th 168 (2d Cir. 2026), the Second Circuit vacated summary judgment for major retailers and manufacturers after concluding that the district court exceeded its gatekeeping role under Federal Rule of Evidence 702. The court reinstated three plaintiff experts whose testimony had been excluded, reviving more than 500 dismissed cases alleging that prenatal acetaminophen exposure caused autism and ADHD. For companies defending complex products liability and mass tort claims, the ruling signals that winning a Daubert motion may no longer end the litigation.

What the Court Decided

The district court had excluded all five plaintiff causation experts and granted summary judgment, finding their methodologies unreliable. The Second Circuit disagreed as to three of them. Writing for a unanimous panel, Senior Circuit Judge Calabresi held that the district court repeatedly substituted its own scientific judgments for those of qualified experts working within accepted methodologies, imposed requirements that no scientific authority supported, and treated study limitations as categorical bars to reliance rather than issues of weight for the jury.

The court was careful to frame what it was not deciding. The ruling does not establish that acetaminophen causes autism or ADHD. It holds only that three credentialed scientists applying accepted epidemiological methods offered opinions that a jury, not a judge, should evaluate.

The court affirmed the exclusion of two other plaintiff experts. One failed to explain how he weighted the Bradford Hill factors he applied. The other mischaracterized the studies underlying his dose-threshold conclusion. The distinction matters: methodology alone does not guarantee admissibility. Transparent, defensible application of that methodology does.

Key Takeaways

• Daubert is a threshold, not a finish line. A successful exclusion motion eliminates testimony, but appellate courts will scrutinize whether the district court crossed from gatekeeping into verdict-substitution. Defense strategy must account for the possibility that excluded experts will return on remand or appeal.
• Expert methodology documentation is now a litigation asset. The reinstated experts survived because their reports acknowledged contrary evidence, explained interpretive choices, and connected conclusions to practices accepted in their fields. Identifying genuine methodology gaps early matters far more than attacking conclusions alone.
• Scientific disagreement does not equal unreliability. Where qualified experts apply accepted methods and reach different conclusions on a genuinely contested question, both sides may present their views to the jury.
• Federal preemption arguments require close analysis. The court rejected defendants' argument that FDA pregnancy labeling requirements preempted state failure-to-warn claims, finding that the regulations required a general warning without prohibiting supplemental product-specific warnings.

What to Watch

The revived cases return to the Southern District of New York, where defendants have said they will renew Rule 702 challenges. Companies defending similar mass tort or products liability MDLs should treat this decision as a recalibration of how much work Daubert can do. Trial preparation, expert vetting, and litigation strategy all need to be built around the assumption that the case may reach a jury.