Awaiting Judge Rosenstengl’s Determination on Daubert Hearings in Paraquat Litigation 

The series of Daubert hearings, pivotal in the ongoing multidistrict litigation concerning Paraquat, concluded after intensive deliberations from August 21 to 24, under the adjudication of MDL Judge Nancy Rosenstengl. The proceedings, marked by vigorous debate, centered predominantly on the testimony of Dr. Michael Wells, the plaintiffs’ principal general causation expert. His appearance was at the behest of Judge Rosenstengl, indicating the weight his testimony held in the litigation. 

Dr. Michael Wells’ Testimony: A Focal Point of the Daubert Hearings 

Dr. Wells’ testimony involved a meta-analysis of seven epidemiological studies that examined the potential link between Paraquat exposure and Parkinson’s Disease, with his findings suggesting an odds ratio of 2.8. The defendants, Syngenta and Chevron, challenged his methodology, claiming an oversight of three larger, more recent studies that contradicted his conclusions. They used critical language, implying that Dr. Wells selectively reported data to support his position, thus questioning the reliability of his analysis. 

In response, Dr. Wells, supported by plaintiffs’ counsel Eric Kennedy, contended that the newer studies were of inferior quality and methodologically distinct, thereby justifying their exclusion from his analysis. Furthermore, the defense’s citation of past instances where Dr. Wells’ expert testimony was purportedly disregarded was met with firm refutations from counsel Kennedy, who insisted these references were misrepresented. 

Defense Challenges and Plaintiff Rebuttals in Paraquat Case

Throughout the hearings, Judge Rosenstengl was discerning, alluding to the Seventh Circuit’s Manpower decision which admonished lower courts against exceeding their ‘gatekeeping’ mandate on Daubert motions, reminding them of the jury’s exclusive role in determining the veracity and significance of expert testimony. Her allusions to this precedent appeared to indicate a meticulous approach in her pending decisions concerning the admissibility of Dr. Wells’ and other experts’ testimonies. 

Following the conclusion of the hearings, Judge Rosenstengl requested additional post-hearing briefs from the parties, extending to 20 pages, which were filed on September 8, 2023. She acknowledged the extensive review that lay ahead, leading to the deferment of the first bellwether trial, originally scheduled for October, to an undetermined later date. This rescheduling is contingent on her potential denial of the Daubert motions seeking to exclude Dr. Wells and other expert witnesses offered by the plaintiffs, marking the third postponement of the trial. 

Given the complexities of the arguments presented, the anticipation of the outcomes of the Daubert motions has become increasingly challenging. Judge Rosenstengl exhibited no clear inclination towards a decision at the hearings’ conclusion, underscoring the unpredictability of the ruling. 

A definitive judgment on the Daubert motions is expected before the close of the year, a decision that will have significant implications for the direction of the litigation.