California cannot require companies to place warning labels on glyphosate products, a federal judge affirmed in a ruling issued Tuesday that questions the benefits of Proposition 65, which is meant to inform the state’s residents about cancer-causing chemicals.

“Given the evidence in the record, the court questions whether California has shown that requiring a Proposition 65 warning for glyphosate directly advances the law’s stated interest in informing Californians about exposures to chemicals that cause cancer,” U.S. District Judge William Shubb in Sacramento said in his order upholding a preliminary injunction he issued in February.

The label requirement for products containing glyphosate, the active ingredient in Monsanto's Roundup herbicide, was scheduled to go into effect in July, but the judge's ruling has scotched those plans. While not a final ruling in the case, Shubb's injunction can be seen as a strong indication of how he will ultimately rule on summary judgment.

“California is attempting to implement a policy that would cause damage to American farmers,” Chandler Goule, chief executive officer for the National Association of Wheat Growers (NAWG), the lead plaintiff in the case, said in a news release. “The facts and science are on our side, which shows that glyphosate is safe for use. Farmers and growers are defending U.S. agriculture against California’s false and misleading Prop 65 labeling requirement, and maintaining this preliminary injunction is another win for them."

Shubb rejected the state’s motion to reconsider his February ruling, in which he found that forcing companies to use labels warning that glyphosate is known to cause cancer would be misleading to consumers.

Chandler Goule, NAWG

A collection of commodity groups led by NAWG, along with glyphosate manufacturer Monsanto and trade groups such as CropLife America and the Agricultural Retailers Association sued the state in November, claiming that the warning labels required by California’s Proposition 65 violated their First Amendment rights by forcing them to make false and controversial claims.

Shubb agreed. “Given the heavy weight of evidence in the record that glyphosate is not in fact known to cause cancer, the required warning is factually inaccurate and controversial,” he said in February.

California asked him to reconsider his ruling, offering what it said was new evidence, such as a newly adopted “no significant risk level” of 1,100 micrograms per day. That level, also known as a “safe harbor level,” is meant to guide businesses in determining whether they are in compliance with the law.

Shubb, however, said the safe harbor level and citations supporting the conclusion of the World Health Organization's International Agency for Research on Cancer – whose monograph finding that glyphosate probably causes cancer in humans serves as the basis for the Prop 65 listing – had no bearing on his earlier decision.

“Even assuming these citations constituted new evidence . . ., additional support for the IARC determination does not change the fact that the overwhelming majority of agencies that have examined glyphosate have determined it is not a cancer risk,” Shubb said in his order. “Once again, the court’s analysis here is not whether the IARC’s determination is persuasive or supported by competent evidence, but rather whether a warning conveying the message that glyphosate causes cancer is factual and uncontroversial.”

Shubb criticized alternative warnings proposed by California. One said, “WARNING: This product can expose you to glyphosate, a chemical listed as causing cancer pursuant to the requirements of California law. For more information go to”   

Shubb said the the warning was not much different from the one he already rejected. “Stating that a chemical is listed as causing cancer 'pursuant (to) the requirements of California law' conveys essentially the same message to consumers as stating that a chemical is known to the state of California to cause cancer,” he said.

“Further, California cannot remedy this warning by simply pointing consumers to a website discussing the debate,” the judge said. “It would seem likely that few, if any, consumers will actually visit the website, meaning that as a practical matter this website will not provide the necessary context that might render this warning factual and uncontroversial.”

The second warning proposed by California reads: “WARNING: This product can expose you to glyphosate, a chemical listed as causing cancer pursuant to the requirements of California law. The listing is based on a determination by the United Nations International Agency for Research on Cancer that glyphosate presents a cancer hazard. The U.S. Environmental Protection Agency has tentatively concluded in a draft document that glyphosate does not present a cancer hazard. For more information go to”

Shubb said the warning is not new evidence because California could have proposed it to the court back when it first heard arguments for and against a preliminary injunction.

The state had, in fact, “specifically rejected the court’s proposal of a warning that would state that glyphosate was a carcinogen as ‘determined by one of the agencies but not by the others' because such language would ‘dilute’ the warning,” he said in his ruling, quoting the state’s attorney in a hearing before the court.

The second proposed warning “is also deficient because it conveys the message that there is equal weight of authority for and against the proposition that glyphosate causes cancer, or that there is more evidence that it does, given the language stating that the EPA’s findings were only tentative, when the heavy weight of evidence in the record is that glyphosate is not known to cause cancer,” Shubb said.

The judge indicated that California has a difficult task in implementing Proposition 65 as to glyphosate, saying that it “appears that a warning properly characterizing the debate as to glyphosate’s carcinogenicity would not comply with Proposition 65 and the applicable regulations and thus would not advance a substantial state interest.”  

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