Investing.com -- Bayer AG (ETR: BAYGN ) is seeking a review by the U.S. Supreme Court of litigation concerning the weedkiller Roundup through its indirect subsidiary Monsanto (NYSE: MON ). The petition for a writ of certiorari was filed today in the Durnell case, three business days after the Missouri Supreme Court’s decision.

Bayer (OTC: BAYRY ) argues that a split among federal circuit courts in the Roundup personal injury litigation warrants a review and resolution by the Supreme Court. The company believes that state-based failure-to-warn claims should be preempted by federal law. The ongoing litigation also threatens Monsanto’s ability to continue to supply glyphosate-based products to farmers and other professional users.

The company asserts that the security and affordability of the food supply depend on having innovative agricultural tools like Roundup available to farmers with uniform and science-based labels. The company is facing litigation industry costs in the hundreds of millions of dollars, based on a single outlier report that is now a decade old, in an effort to punish the company for marketing a product without a cancer warning.

Bayer argues that the Third Circuit Court of Appeals was correct when it unanimously held in Schaffner that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) preempted the plaintiff’s failure-to-warn claim. In Durnell, the jury’s verdict rests solely on the claim that Missouri law requires the company to warn that Roundup is carcinogenic, a warning that EPA rejects.

The 9th and 11th Circuits and Missouri’s intermediate appellate court have reached different conclusions on the preemption question and the petition argues that state and federal courts require guidance that only the U.S. Supreme Court can provide. The petition states that courts in Hardeman, Carson and Durnell erred because they ignored EPA regulations.

The petition also notes that there is preemption language similar to FIFRA in statutes regulating medical devices, poultry products, meat and motor vehicles that make resolution of this preemption split even more important.

Monsanto’s petition argues that Durnell’s state-based failure-to-warn claim also should be dismissed under implied preemption because it is impossible for the company to comply with both federal and state requirements.

Monsanto filed two prior petitions in the Roundup litigation on the federal preemption question with the U.S. Supreme Court, in Hardeman and Pilliod, both filed before the U.S. Court of Appeals for the Third Circuit ruled in the company’s favor in Schaffner in August 2024.

In October 2023, Durnell was tried in Missouri Circuit Court for the City of St. Louis and the jury returned a verdict in favor of the plaintiff. The company appealed the verdict in August 2024 and the Missouri Court of Appeals, Eastern District upheld the verdict in February 2025. Monsanto promptly filed a writ to transfer the case to the Missouri Supreme Court and it declined review on April 1, 2025, making it ripe for U.S. Supreme Court review and the petition filed just three days later.

As of 3:30 ET, Bayer stock closed in German trading down 5.5%, likely due to the escalating global trade war, which was sparked by U.S. President Donald Trump’s Wednesday tariff announcement.

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