In August 2025, the Ninth Circuit affirmed a district court’s decision to exclude an expert’s causation opinion as unreliable and grant summary judgment in favor of a herbicide manufacturer. The case, which arose from claims that exposure to an herbicide caused the plaintiff’s blood cancer, underscores the critical importance of rigorous and well-supported expert analysis in toxic tort litigation and the judiciary’s gatekeeping role under Federal Rule of Evidence 702.1
The United States Court of Appeals for the Third Circuit, in Schaffner v. Monsanto, No. 22-3075 (3rd Cir. 2024), recently held that a state-law duty to warn claim was expressly preempted by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). To reach the conclusion, the 3rd Circuit diverged from the 9th and 11th Circuits, thus creating a split between circuits and providing an opportunity for the United States Supreme Court to step in and make a definitive ruling on FIFRA preemption. If the Supreme Court were to adopt the 3rd Circuit’s reasoning, FIFRA would preempt any state-law duty to warn claims that were inconsistent with EPA’s approved label for products containing glyphosate.