Tuesday, April 28, 2026

Supreme Court Weighs Whether Federal Law Shields Bayer From Roundup Cancer Lawsuits

By ANDRÈ COLEMAN, Managing Editor

The U.S. Supreme Court heard arguments Monday in a closely watched case that could determine whether Bayer can be held liable under state law for failing to warn that its Roundup weed killer may cause cancer.

At issue is whether federal pesticide regulations preempt thousands of state lawsuits alleging that Roundup’s active ingredient, glyphosate, causes non-Hodgkin lymphoma and that the company failed to provide adequate warnings.

The Los Angeles County Board of Supervisors banned the controversial spray in 2019 after it was revealed it was being used near a heliport in unincorporated Pasadena, adjacent to District 4.

Later it was discovered that county crews were also using Roundup as part of the sediment removal project at Devil’s Gate Dam, raising fears of local water supply contamination.

In July 2019, it was revealed that a landscaper had used a generic version of the weed killer in a playground and courtyard at a Caltech graduate housing complex, exposing children and parents to the chemical. In response, Caltech banned the use of such pesticides for weed management at its student housing facilities.

The City stopped using Roundup on City property in 2018.

The case stems from a Missouri man who won a $1.25 million judgment after claiming prolonged exposure to Roundup caused his illness.

Bayer, which acquired Monsanto in 2018, is asking the justices to overturn such verdicts, arguing that the Environmental Protection Agency has repeatedly found glyphosate unlikely to cause cancer and approved product labeling without a cancer warning.

The classification of glyphosate as a possible carcinogen remains a point of dispute among regulators.

The Environmental Protection Agency has said it does not consider glyphosate to be a cancer-causing agent, while state regulators have listed the chemical as a carcinogen under Proposition 65, formally known as the Safe Drinking Water and Toxic Enforcement Act of 1986.

In April 2019, a California appellate court ruled that the state can require labeling of products containing glyphosate as toxic under Proposition 65.

The debate has extended beyond courtrooms and into food safety concerns.

Glyphosate has been detected in a range of oat-based cereals and snack products, many of them marketed to children. Testing cited by CBS News found the chemical in 21 such products, with all but four exceeding levels that some health advocates consider unsafe for children.

The issue has also been the subject of prior litigation. In February 2018, a federal judge temporarily blocked the state from requiring cancer warning labels on food products containing trace amounts of glyphosate.

Food manufacturers and chemical companies maintain that the product is safe when used as directed. General Mills, which produces several oat-based snacks, has said food safety is its “top priority” and noted that pesticides are used in “the majority of foods we all eat,” adding that federal regulators determine acceptable exposure levels.

Bayer, which manufactures Roundup, has similarly said glyphosate levels found in food and the environment are “far below” limits established by federal regulators to protect human health.

Critics dispute those claims. The Environmental Working Group has accused Bayer of “spreading misinformation about pesticide residues” and has called for stricter oversight and lower exposure thresholds.

Bayer has argued in court filings that pesticide regulations are well-established and that glyphosate levels fall within federally approved safety standards.

During oral arguments, several justices appeared divided over whether federal law governing pesticide labeling overrides state-level failure-to-warn claims.

A lawyer for Bayer told the court that allowing state lawsuits to proceed would undermine federal authority and create inconsistent labeling requirements across the country.

“Federal law does not permit states to impose labeling requirements that conflict with the EPA’s scientific determinations,” the attorney said.

Lawyers representing plaintiffs argued that federal approval should not shield companies from liability when new evidence or competing scientific findings raise concerns about product safety.

“State law plays a critical role in protecting consumers when federal regulation falls short,” an attorney for the plaintiffs told the court.

The outcome could have sweeping implications. Bayer faces tens of thousands of similar lawsuits nationwide, many of which could be dismissed if the court rules in the company’s favor.

A decision against Bayer would allow those cases to proceed and potentially expose the company to billions in damages.

The case also highlights broader tensions between federal regulatory authority and state consumer protection laws, particularly in areas involving public health and environmental risk.

The justices are expected to issue a ruling by late June.