Court Dismisses Monsanto Challenge to California Cancer Chemicals List

A California state court judge has rejected chemical maker Monsanto’s legal challenge to an important provision of Proposition 65, the 1986 voter initiative that requires California’s Governor to maintain a public list of chemicals known to the state to cause cancer. Monsanto was seeking to prevent California from adding glyphosate, the herbicide found in the company’s Roundup products, to the state’s cancer list. On Friday, March 10, Fresno County Superior Court Judge Kristi Culver Kapetan ruled that none of Monsanto’s attacks on the provision were viable and dismissed the case. 

“Monsanto may prefer to keep glyphosate off the Prop 65 list, but that does not empower them to override the choice of California's voters,” said Selena Kyle, a senior attorney with the Natural Resources Defense Council (NRDC).

As the court recognized in its order, “the voters determined that there should be a list of cancer-causing chemicals and substances.” The court also found that “there does not appear to be any chance that Monsanto or [its co-plaintiffs] can amend their complaints to state valid claims under any of the theories they can rely upon.”

Monsanto challenged the California Office of Environmental Health Hazard Assessment’s proposal to add glyphosate to the Proposition 65 list, following a 2015 finding by the World Health Organization’s International Agency for Research on Cancer (IARC) that glyphosate is a probable human carcinogen. Monsanto disagreed with California voters’ choice to make IARC findings an independent ground for adding carcinogens to the Proposition 65 list and argued it was unconstitutional. The court rejected Monsanto’s arguments.

“For thirty years, Proposition 65 has helped inform Californians about their exposure to harmful chemicals. The court's decision upholds that right and will ensure that California continues to promptly list chemicals classified as carcinogens by respected scientific entities,” said Katie Schaefer, a Sierra Club staff attorney.

NRDC, Sierra Club, the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, AFL-CIO, CLC, and the Environmental Law Foundation intervened in Monsanto’s lawsuit, alongside California, and filed a successful companion motion to dismiss.


The Natural Resources Defense Council (NRDC) is an international nonprofit environmental organization with more than 2 million members and online activists. Since 1970, our lawyers, scientists, and other environmental specialists have worked to protect the world's natural resources, public health, and the environment. NRDC has offices in New York City, Washington, D.C., Los Angeles, San Francisco, Chicago, Bozeman, MT, and Beijing. Visit us at and follow us on Twitter @NRDC.


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