The Ninth Circuit’s Latest Word on Expert Testimony: A Cautionary Tale for Expert Witnesses in Toxic Tort Litigation

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….
By: Husch Blackwell LLP