Daubert Challenges For Paraquat Parkinson’s Lawsuits To Be Considered During Aug. 2023 Hearing

Court will consider a series of challenges to the admissibility of expert witnesses about the link between Paraquat and Parkinson's, under the federal Daubert standard.

The U.S. District Judge presiding over all federal Paraquat lawsuits will hold hearings in August 2023, to consider challenges to the admissibility of expert testimony that will be presented at trials to establish that exposure to the weed killer caused Parkinson’s disease among users.

There are currently more than 3,200 product liability lawsuits filed against Syngenta and Chevron in the federal courts, each raising similar allegations that the manufacturers of the controversial herbicide failed to warn farmers and agricultural users about the Paraquat Parkinson’s risks , which research has found may develop after regularly spraying, mixing, transporting or handling the weed killer, even when all recommended safety precautions are followed.

Given common questions of fact and law raised in the litigation, the federal cases have been centralized as part of a Paraquat MDL (multi-district litigation) since June 2021, which is consolidated before U.S. District Judge Nancy J. Rosenstengel in the Southern District of Illinois, for coordinated discovery and pretrial proceedings.

PARAQUAT Parkinson's Lawsuits

Did you get Parkinson's after exposure to Paraquat?

Exposure to the toxic herbicide Paraquat has been linked to a risk of Parkinson's disease.


To help the parties evaluate how juries may respond to certain evidence and testimony that will be presented throughout various claims, the Court previously set an aggressive schedule early in the litigation, which calls for the first Paraquat Parkinson’s lawsuit bellwether trials to begin this October.

In a case management order (PDF) issued on April 21, Judge Rosenstengel scheduled “Daubert” hearings to be held on August 21, to consider the admissibility of each side’s expert witnesses and rule on summary judgment motions that seek to dismiss the lawsuits.

The hearings are named for a series of U.S. Supreme Court decisions, starting with Daubert v Merrell Dow Pharmaceuticals, Inc., which established the rule of evidence in the federal court system for the admissibility of expert testimony, allowing the judge to act as a gatekeeper, ensuring that testimony presented is relevant and based on a sufficiently reliable scientific foundation to allow a jury to consider the evidence.

At the Paraquat Daubert hearings, the Court will consider challenges presented by each side that seek to exclude certain expert witnesses or opinions that may be offered at trial about the link between exposure to Paraquat and Parkinson’s disease. The court will consider the qualifications of each experts, the basis for their opinions and determine whether the proposed testimony will be permitted at trial.

Leading up to the hearings, Judge Rosenstengel has ordered the parties to submit summary judgment and Daubert motions by June 6, with responses to those motions due by July 10 and replies must be filed by July 28.

2023 Paraquat Parkinson’s Lawsuit Update

To help the parties gauge how juries are likely to respond to certain evidence and testimony that will be repeated throughout the litigation, Judge Rosenstengel previously established a “bellwether” process where case-specific discovery has been completed in a group of 16 Paraquat cases selected last year.

Jury selection for the first bellwether test trial is currently scheduled to begin on October 16, 2023, following a final pretrial conference that will be held on October 3.

While the outcome of the early Paraquat jury trials and case-specific discovery in non-bellwether claims will not have any binding impact on other plaintiffs, they are expected to greatly influence the average Paraquat settlement amounts the manufacturers may offer to avoid each individual claim being remanded back to U.S. District Courts nationwide for separate trial dates in the coming years.


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