John Durnell, a gardener, brought suit against Monsanto for manufacture of its weedkiller, Roundup, after long-term exposure to the pesticide, alleging that the exposure was the source of his cancer, non-Hodgkins lymphoma. Roundup contains, as an ingredient, glyphosate—and the core of the litigation, in this, and the thousands of other like suits against Monsanto, is the dispute over whether glyphosate is a carcinogen.

The Environment Protection Agency (EPA) requires registration of pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Central to the EPA regulations is the review and monitoring of labels on the product indicating unreasonable risks to health and safety associated with exposure to the product. With respect to Roundup, the agency has consistently refused to require a warning that glyphosate is a carcinogen.

Durnell’s lawsuit against Monsanto claims a failure to warn of the attendant cancer risks. In response, Monsanto relies on the preemption provision in FIFRA prohibiting states from imposing “any requirements for labeling or packaging in addition to or different from those required under” FIFRA; hence the defense—relied on by the Supreme Court—that Durnell’s failure to warn claim is directly contrary to the EPA’s continuing rejection of any requirement by Monsanto indicating an unreasonable risk of cancer from exposure to the product.

Durnell had prevailed in his Missouri state court suit, where a jury awarded him more than a $1million in damages—an award that was upheld by the state court of appeals, but overturned by the U.S. Supreme Court (7-2), against the backdrop of conflict among lower courts in Roundup litigation, and settlement of thousands of lawsuits by Monsanto. Nonetheless, the Supreme Court’s decision dispatches not just Durnell’s suit, but many thousands of other outstanding, similar claims in other state courts. Still in the works, collateral issues arise from an ongoing federal multidistrict litigation, and a settlement offer by Monsanto to resolve a host of distinct Roundup exposure claims.

It’s difficult to assess the larger impact, if any, on preemption litigation in other settings. Neither this case nor earlier Supreme Court opinions involving tobacco, prescription drug, or medical device preemption claims, among others, elude the straightforward fact that in each statutory/regulatory setting the crux of the matter is whether the agency directives (or non-directives) track the tort claim so clearly as to preclude the tort litigation; and that determination requires a case-by-case inquiry into a question of the clarity of the agency’s position—which is often far from evident. So, it seems likely that Monsanto v Durnell is simply another leading preemption decision that has major consequences for this particular mass tort episode, but leaves considerable room for future disagreement in other settings.

An expert on torts and legislative compensation schemes, Robert L. Rabin is highly regarded for his extensive knowledge of the history and institutional dynamics of accident law. He is a prolific author on issues relating to the functions of the tort system and alternative regulatory schemes and is the co-editor of a classic casebook on tort law. He has served as advisor on the American Law Institute’s Restatement of the Law (Third) of Torts (2012), and Restatement of the Law (Third) of Products Liability (1998). He was also the program director for the Robert Wood Johnson Foundation Program on Tobacco Policy Research and Evaluation, as well as a co-reporter for the American Law Institute Project on Compensation and Liability for Product and Process Injuries, and reporter for the American Bar Association Action Commission to Improve the Tort Liability System.