In re Paraquat: Studious Gatekeeping Exposes and Excludes Made-for-Litigation Testimony

The admissibility of expert testimony is governed by Federal Rule of Evidence 702 and Daubert v. Merrell Dow Pharmaceuticals. Chief Judge Nancy Rosenstengel of the US District Court for the Southern District of Illinois recently applied Rule 702 and Daubert in In re Paraquat Products Liability Litigation, 2024 WL 1659687 (S.D. Ill. Apr. 17, 2024), to exclude the general-causation opinions of the plaintiffs’ expert witness, finding numerous “methodological red flags” with the expert’s analysis. On the same day, the court granted summary judgment to the defendants in four cases in which plaintiffs relied on that expert, concluding that the plaintiffs lacked admissible expert testimony establishing causation.