John Durnell’s case began with a routine act repeated over decades. In St. Louis, he used Roundup to spray weeds along sidewalks and public spaces, believing he was helping improve his neighborhood. Years later, after multiple rounds of chemotherapy for non-Hodgkin lymphoma, a Missouri jury found that exposure to Monsanto’s herbicide had caused his cancer and awarded him $1.25 million in damages.
Now Durnell’s case sits at the center of a Supreme Court battle that could affect thousands of lawsuits brought by people who say Roundup exposure caused devastating illnesses and that Monsanto failed to warn them of the risks.
The dispute before the justices does not ask whether glyphosate causes cancer. Instead, it centers on whether federal law prevents states from allowing failure-to-warn claims against pesticide manufacturers whose labels have been approved by the Environmental Protection Agency.
That question carries consequences well beyond a single herbicide.
At issue is the Federal Insecticide, Fungicide, and Rodenticide Act, known as FIFRA, which governs pesticide registration and labeling. Monsanto, now owned by Bayer, argues that because the EPA approved Roundup’s label, state-law claims like Durnell’s are preempted.
Representing Monsanto, attorney Paul Clement told the court that permitting juries to impose additional warning obligations would disrupt national uniformity and expose manufacturers to what he called “crippling liability.”
He also argued, “You shouldn’t let a single Missouri jury second guess that judgment.”
That judgment, he said, belongs to federal regulators.
Several justices appeared receptive to concerns about maintaining one nationwide standard, but oral arguments also revealed unease over what Monsanto’s theory could mean for state authority and consumer protections.
Chief Justice John Roberts pressed the breadth of the argument, asking, “The states cannot do anything?”
Clement acknowledged that states might ban a pesticide outright, but argued they cannot require cancer warnings beyond what federal regulators approve.
Justice Neil Gorsuch questioned that distinction, suggesting it made little sense for states to have the power to prohibit a product but not warn residents about alleged risks.
Justice Ketanji Brown Jackson focused on how science can evolve long before regulators revisit approvals.
“There’s a 15-year window between when that product has to be re-registered again and lots of things can happen in science, in terms of development about the product,” she said.
Her question underscored a central fault line in the case. If scientific evidence changes faster than regulation does, critics argue, should companies still be insulated from warning claims.
That concern has shadowed Roundup litigation for years.
Glyphosate, the active ingredient in Roundup, is among the most widely used herbicides in the world. The World Health Organization has classified it as “probably carcinogenic to humans,” and researchers have linked exposure to a range of health and ecological harms.
Among evidence cited in the litigation is a 2023 study linking Roundup exposure to liver and metabolic disease in children. Public health concerns have also been amplified by a March letter signed by 70 experts urging immediate regulatory action.
“The evidence that glyphosate and GBHs [glyphosate‐based herbicides] harm human health at levels of current use is now so strong that no additional delays in regulation of glyphosate can be justified,” the letter stated.
The letter continued, “Regulatory agencies in countries around the world should treat glyphosate and GBHs as hazardous, as some countries have started to do. Agencies should act without further delay to limit their use, or eliminate them if legally required, to protect public health.”
But despite such warnings, the EPA has continued to maintain glyphosate can be used safely and has not required cancer warnings.
Monsanto’s legal strategy depends heavily on that fact.
The Trump administration reinforced that position during oral arguments, backing Monsanto and breaking with the federal government’s earlier position under President Joe Biden.
Sarah Harris, principal deputy solicitor general, argued, “Missouri thus requires adding cancer warnings but federal law requires EPA to approve new warnings and tasks EPA with deciding what label changes would mitigate any health risks. State law must give way.”
That intervention elevated the case from a corporate liability fight into a broader dispute over federal regulatory power.
Durnell’s attorney Ashley Keller argued that EPA approval should not erase states’ traditional role in protecting residents through tort law.
“Things slip through the cracks with that agency,” he said.
Critics say the case exposes longstanding concerns about the EPA’s pesticide oversight.
J.W. Glass, senior EPA policy specialist at the Center for Biological Diversity, sharply criticized the agency’s record.
“Any honest assessment of the [EPA] pesticide office’s track record can only conclude that it has failed catastrophically at assessing the health risks of dangerous pesticides,” Glass said.
He added, “Considering the EPA has declined to require cancer labels on 99 percent of the pesticide products that contain chemicals the agency itself has found to be probable carcinogens, why would anyone believe that Americans’ health is being looked out for by the EPA or the pesticide industry?”
Those concerns have fueled opposition to a ruling that could narrow legal recourse for people harmed by pesticides.
Tarah Heinzen, legal director at Food & Water Legal Watch, warned that the implications stretch far beyond Bayer.
“Bayer is intent on preserving its right to harm at all costs—a pursuit the Trump administration is all too willing to endorse,” Heinzen said.
She added, “This case threatens to close the courthouse doors to the many Americans harmed by pesticides. Should the Supreme Court hold that the Environmental Protection Agency’s failed pesticide regulatory scheme preempts state failure to warn lawsuits, leaving tens of thousands of sick Americans without legal recourse, Trump and his industry-dominated EPA will be to blame.”
The financial stakes are also enormous.
Bayer has already spent nearly $11 billion settling claims related to glyphosate exposure. A ruling embracing Monsanto’s arguments could significantly weaken remaining litigation and provide major relief from future liability.
The company has also gained support beyond the courtroom. In February, the Trump administration issued an executive order classifying glyphosate production as in the national security interest, a move critics viewed as further evidence of chemical industry influence.
Supporters of Monsanto’s position argue the case is about preventing fragmented regulation and protecting scientific determinations made through federal review.
Opponents argue it is about whether federal approval can become a shield against accountability even when emerging science raises new questions.
The tension reaches beyond Roundup.
The ruling could affect toxic tort litigation more broadly, influencing how courts handle claims involving federally regulated products and whether state juries retain power to hold manufacturers liable when warnings are alleged to be inadequate.
For Durnell and many others, the dispute is not abstract.
It concerns whether those who say they were harmed by a widely used chemical retain access to courts when regulators have declined to require stronger warnings.
For Bayer, it could shape the future of one of the largest product liability battles in modern history.
And for the Supreme Court, the case presents a larger question about who decides how risk is disclosed in American life: federal agencies, states, juries, or some combination of all three.
As the justices prepare their ruling, the warning from the 70 experts continues to frame the broader stakes.
“The evidence that glyphosate and GBHs [glyphosate‐based herbicides] harm human health at levels of current use is now so strong that no additional delays in regulation of glyphosate can be justified.”
COMMENTS