The United States Supreme Court ruled 7-2 on Thursday that federal pesticide labelling law preempts state lawsuits alleging Monsanto, now owned by Bayer, failed to warn consumers about cancer risks from its Roundup weedkiller. The decision in Monsanto v. Durnell means that because the Environmental Protection Agency approved a label without a cancer warning, individual states cannot impose additional requirements. The ruling strips the legal foundation from thousands of pending claims, and Bayer’s share price rose by as much as 17 per cent in Frankfurt trading.

Bayer, headquartered in Leverkusen, Germany, had argued that the EPA’s determination that glyphosate is not carcinogenic when used as directed should override state-level demands. The company said the ruling provides regulatory clarity for science, farmers, and industries reliant on innovation. Viewed from Washington, the decision reinforces the supremacy of federal agency approvals in product liability cases, a principle that could extend to other sectors. The two dissenting justices, Ketanji Brown Jackson and Neil Gorsuch, did not accept that federal law entirely blocks state consumer protection actions.

The ruling has drawn sharp criticism from the Make America Healthy Again (MAHA) movement, a coalition of health-conscious voters who supported Donald Trump’s re-election. MAHA activists, as reported by US media, view the administration’s decision to back Monsanto in the case as a betrayal of campaign promises to challenge corporate influence on health. Some MAHA figures warn that the outcome could depress turnout among their supporters in the 2026 midterm elections, while others see it as a mobilising issue. The White House stated that the president remains committed to the MAHA agenda and that an earlier executive order prioritising glyphosate production was a national security measure, not an endorsement of the product.

The litigation originated with Bayer’s 2018 acquisition of Monsanto, which brought a wave of lawsuits linking Roundup to non-Hodgkin’s lymphoma. Bayer has already paid more than $10 billion in settlements and verdicts. The company is now seeking final court approval for a proposed $7.25 billion class settlement to resolve current and future claims. With the Supreme Court ruling, Bayer expects many existing lawsuits to be dismissed and future ones blocked. The settlement plan is pending before a Missouri state court, and its approval would mark a significant step toward closing the chapter on the Roundup litigation.