Supreme Court Hears Monsanto v. Durnell: Federal Preemption and Roundup Liability in Focus

The U.S. Supreme Court on Tuesday heard oral arguments in Monsanto Co. v. Durnell, a case with limited constitutional significance but major implications for the business community. The dispute centers on whether federal regulations preempt state tort claims alleging harm from Bayer’s Roundup herbicide.

The plaintiff sued Monsanto—owned by Bayer—for $1.25 million in compensatory damages, arguing the company failed to adequately warn about potential health risks. Bayer countered that the EPA did not require additional warnings, asserting that state tort claims are preempted by federal regulations. The Court’s conservative justices appeared divided on the preemption issue, a recurring point of contention in their jurisprudence.

Key Questions Before the Court

• Does federal preemption apply when an agency interprets a statute through regulation?
• After Loper Bright, do courts or agencies decide the preemptive effect of federal law?
• Can state courts interpret federal statutes to determine preemption in tort cases?

Justice Clarence Thomas, a former Monsanto legal advisor, reminded parties not to conflate herbicides with pesticides during arguments. His skepticism toward federal preemption aligns with his federalist leanings, as seen in his recent Hencely opinion.

Justice Neil Gorsuch also expressed reservations about agency deference, while Justices Brett Kavanaugh, John Roberts, and Samuel Alito seemed inclined toward broad federal preemption to shield businesses like Monsanto from inconsistent state rulings. Justice Amy Coney Barrett’s stance remained unclear.

Ashley Keller, counsel for the respondent, received minimal questioning—often a sign of judicial skepticism. After nearly two hours of arguments in an unrelated Fourth Amendment case, the Justices appeared fatigued, allowing Keller uninterrupted time toward the end. Typically, the side facing fewer questions faces tougher odds.

Justice Alito broke his silence only to question counsel about Loper Bright, the landmark case overturning Chevron deference. The decision raises critical questions: If agencies no longer receive deference, who interprets federal statutes—courts or agencies? And can state courts independently assess preemption in tort suits?

The Court’s eventual ruling could redefine the balance between federal regulatory authority and state tort law, with sweeping consequences for industries regulated by the EPA and other agencies.