US Supreme Court blocks state failure-to-warn lawsuits over Monsanto Roundup labeling

The U.S. Supreme Court on Thursday ruled 7-2 in favor of Monsanto in a decision expected to sharply curtail state failure-to-warn lawsuits over Roundup’s cancer warnings.

The case, Monsanto v. Durnell, centered on whether federal pesticide law preempts state-law claims that Roundup should have carried a warning about cancer risk when the Environmental Protection Agency did not require that label change. The court said it does.

The ruling is likely to affect thousands of pending lawsuits against Bayer, which acquired Monsanto in 2018 and now owns the Roundup business. AP reported that Bayer has faced about 200,000 Roundup-related claims and has proposed settlements totaling more than $23 billion.

John Durnell, a Missouri resident, sued after saying he developed non-Hodgkin’s lymphoma following more than 20 years of Roundup use. A jury awarded him $1.25 million before the case reached the Supreme Court.

What the court decided

The decision turns on federal preemption, the legal principle that federal law can override conflicting state claims. In practical terms, the ruling strengthens Bayer’s argument that it cannot be held liable under state law for failing to include a cancer warning when the EPA did not require one.

That makes the ruling a major setback for plaintiffs who built cases around warning labels rather than other theories of liability. It also gives lower courts a stronger basis to dismiss or narrow similar Roundup failure-to-warn suits already working through the system.

Justice Brett Kavanaugh was among the justices in the majority, while Justice Ketanji Brown Jackson was among the dissenters, according to the reporting package on the case.

How the case got here

Roundup litigation has for years centered on whether Monsanto failed to warn users that glyphosate, Roundup’s active ingredient, could cause cancer. Monsanto and Bayer have argued that federal pesticide rules and EPA oversight should control the label, not state tort law.

Durnell’s case became one of the high-profile test cases in that fight. He said he used Roundup for more than two decades before developing non-Hodgkin’s lymphoma, and the Missouri jury’s $1.25 million verdict put the dispute on the Supreme Court’s docket.

The June 25 ruling now resolves that warning-label question in Bayer’s favor.

Why it matters

The immediate effect could be broad. Thousands of existing Roundup failure-to-warn claims may now be blocked or cut off, and Bayer can use the ruling to press for faster resolution of remaining litigation.

The decision also strengthens the role of federal pesticide regulation in a dispute shaped by competing views of glyphosate’s safety. The EPA has maintained that glyphosate is unlikely to be carcinogenic when used as directed.

That has not ended the controversy. The World Health Organization’s cancer research arm classified glyphosate as probably carcinogenic in 2015, and that split has fueled years of litigation and public debate.

What happens next

Lower courts will now apply the ruling to pending Roundup cases. Some judges may dismiss state warning claims outright, while others could consider whether any alternative theories survive.

Plaintiffs may shift toward other claims, including design-defect theories where those remain available. The Supreme Court’s ruling makes warning-based cases much harder to pursue, but it does not end all Roundup-related litigation by itself.

Bayer is likely to treat the decision as a major legal win after years of costly pressure from the litigation. Axios reported that Monsanto welcomed the ruling and described it as good for science, farmers and regulatory clarity.

The broader business effect could be significant if the ruling helps narrow Bayer’s exposure and changes the pace of settlement talks. Still, the scientific and political debate over glyphosate is not resolved by the court’s legal holding.