Paraquat Legal Developments: Daubert Hearings Are Over

William V on September 19, 2023

The hearings on the Daubert motions took place from August 21-24 before MDL Judge Nancy Rosenstengl. The oral arguments were, as expected, very contentious and at a very high level. The sole live witness at the hearing, specifically requested by the Judge, was Dr. Michael Wells, plaintiffs’ only general causation expert.  The parties’ arguments on their respective motions to exclude other expert witnesses did not generate anywhere near the same time and heat as the arguments over Dr. Wells — which only makes sense since he is the linchpin of plaintiffs’ case.

Dr. Wells did a meta-analysis of seven (7) prior epidemiological studies of the causal link between exposure to Paraquat and Parkinson’s Disease, and he concluded that the odds ratio was 2.8. Syngenta and Chevron argued that he failed to properly consider let alone give proper weight to three more recent and much larger epidemiological studies, which did not show a causal link between Paraquat and Parkinson’s Disease — and used defendant boilerplate words such as “cherry-picking” to characterize his analysis as unreliable and thus warranting exclusion.  Dr. Wells and plaintiffs’ counsel Eric Kennedy strongly rebutted those attacks, emphasizing Dr. Wells did consider the other studies but gave them no weight in his analysis because they were lower quality and designed differently than the particular studies he relied upon.

Defendants also cited three prior litigations where Dr. Wells’ expert opinions had been allegedly excluded but plaintiffs’ counsel Kennedy seemed to adequately rebut those assertions as gross mischaracterizations.

In her questioning of counsel during the hearings, Judge Rosenstengl brought up the Seventh Circuit’s Manpower ruling (where that Court had reversed a district court judge for improperly excluding an expert on a Daubert motion). The language in that Seventh Circuit opinions warns district court judges not to overstep their limited role as “gatekeeper” on Daubert motions and intrude on the exclusive province of the jury as sole arbiter of the credibility and weight of expert witnesses’ opinions The Judge’s references to Manpower seemed somewhat heartening, signaling that she intends to tread carefully while wrestling with the critical question of allowing or excluding Dr. Wells and the other experts (on both sides).

At her request the parties filed 20-page post-hearing briefs on September 8, 2023.

She warned that she had much additional reading, and rereading, to do and, consequently, booted the upcoming October date for the first bellwether trial to some as-yet-unknown future date – all premised of course on her denying the Daubert motions aimed at excluding Dr. Wells (and excluding plaintiffs’ other expert witnesses) This is the third rescheduling of the trial.

It’s extremely hard to handicap the outcome of the Daubert motion aimed at Dr. Wells. The Judge did not appear to be anywhere close to making up her mind, or even leaning in one direction, by the end of the hearings.

Rulings on all the Daubert motions will hopefully be issued before year end.

Recent Judicial Proceedings in Paraquat Multidistrict Litigation Await Decision by Judge Rosenstengl

Daniela P on September 19, 2023

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.