A U.S. appeals court recently ruled that California lacks the authority to enforce a regulation mandating cancer warnings on glyphosate, the main active compound in Monsanto's widely used herbicide Roundup, which was acquired by Bayer in 2018. The Ninth Circuit ruled Nov. 7 that the most recent warning issued by the state of California perpetuates the assertion that the chemical is hazardous, a claim deemed "at best disputed," Law360 reported.

The Ninth Circuit’s split panel upheld a summary judgment by a California federal judge, affirming the invalidity of the state's updated glyphosate safe harbor warning. The published opinion emphasized that the most recent warning would compel companies to communicate a "controversial, fiercely contested message that they fundamentally disagree with," rendering it unsustainable.

In Nov. 2017, a coalition comprised of agricultural entities and business stakeholders, including Monsanto, the National Association of Wheat Growers, and the National Corn Growers Association, initiated legal action against California, arguing that a warning label for glyphosate was compelled speech, tantamount to an infringement of their First Amendment rights. 

Since that initial lawsuit against California, the Golden State’s Office of the Attorney General has proposed multiple versions of a glyphosate cancer warning under the state’s Proposition 65. In January 2023, The California Environmental Protection Agency's Office of Environmental Health Hazard Assessment finalized a revised glyphosate safe harbor warning. That warning was defended by Laura Zuckerman, the Supervising Deputy Attorney General of California before the Ninth Circuit in late April.

However, the appellate court ruled that, despite attempts to revise the warning to accommodate First Amendment principles, the latest iteration remains insufficient and upheld U.S. District Judge William B. Shubb's June 2020 order in favor of Monsanto and the other challengers.

The panel underscored the absence of a scientific consensus regarding glyphosate's carcinogenic properties, noting that although the International Agency for Research on Cancer (IARC) identified it as a probable human carcinogen in 2015, this viewpoint is not universally accepted within the scientific community. 

Consequently, the proposed warning stating that "glyphosate is known to cause cancer" was deemed contentious and not purely factual, as the term "known" carries legal nuance not readily apparent to consumers without context.

In light of the lack of unanimity on the chemical's impact, the panel asserted that California can only mandate commercial speech if it satisfies the requirements of intermediate scrutiny. The court concluded that none of the proposed glyphosate Proposition 65 warnings met these criteria, rendering the application of the warning unconstitutional.

Judge Mary M. Schroeder of the Ninth Circuit dissented, advocating for a remand of the latest glyphosate warning to the district court for an initial assessment of its sufficiency. Schroeder argued that the majority should have scrutinized the warning's specific content instead of focusing on the overall message.

Additionally, Judge Schroeder noted that the District Court should reconsider the scientific record of glyphosate, especially because there is no clear guidance from the U.S. Supreme Court when it comes to free speech and product liability. 

More than 165,000 Roundup claims have been filed by consumers. Bayer settled approximately 90% of those claims in 2020 with a $10.9 billion settlement. The company still faces over 40,000 claims, including over 4,000 that are consolidated in multidistrict litigation (MDL).