A federal court in California has entered a permanent injunction blocking enforcement of the state's Proposition 65 cancer warning for diethanolamine (DEA) in cosmetics and personal care products, after the state's attorney general conceded the case without contest.
The action reflects the fourth consecutive victory for industry groups in First Amendment cases, a string of rulings that one industry attorney described as the most significant erosion of California’s Prop 65 warning regime in its 40-year history.
Judge Daniel Calabretta of the US District Court for the Eastern District of California signed the permanent injunction on 23 June, implementing a joint stipulation agreement submitted the same day by the Personal Care Products Council (PCPC) and California attorney general Rob Bonta.
The order permanently enjoins the attorney general's office and private enforcers from filing or prosecuting new enforcement actions for the DEA warning in cosmetics and personal care products.
It also includes a broader declaration that "the Proposition 65 warning requirement for cancer as applied to diethanolamine cannot be constitutionally enforced".
Quick victory
The order came less than four months after the PCPC filed a complaint in federal court challenging the constitutionality of the Office of Environmental Health Hazard Assessment (OEHHA)’s cancer warning requirement for DEA.
PCPC argued the warning requirement violated the First Amendment by compelling its members to carry a statement characterising DEA as a known human carcinogen when there is no scientific consensus on the substance’s carcinogenicity.
In the joint stipulation, California’s attorney general’s office said it disputes the contention that the DEA warning requirement violates the First Amendment.
However, the parties agreed it would be in their interests not to litigate the issue, citing the current state of the relevant science, the standards articulated in three recent court decisions involving Prop 65 warnings and their "review, analysis, and application of the facts and the law".
The order leaves open the possibility that the attorney general's office could return to court to seek dissolution of the injunction if the underlying science or law changes sufficiently.
The PCPC welcomed the action.
"This outcome reinforces that Prop 65 warning requirements must be grounded in sound science and that the state cannot compel speech that is misleading or unsupported by scientific consensus," said Emily Manoso, PCPC’s executive vice president of legal and regulatory affairs and general counsel.
The attorney general's office did not respond to a request for comment.
‘First real cracks in 40 years’
The DEA ruling is the fourth consecutive First Amendment win against a Prop 65 warning requirement, following similar decisions involving glyphosate, acrylamide in food products, and most recently, an August 2025 judgment in favour of PCPC regarding titanium dioxide warnings for cosmetics.
Industry attorneys described the string of outcomes as a watershed moment for the law.
"These cases represent the first real cracks in the law's 40-plus year history," said Dennis Raglin, an attorney at Carlton Fields.
"There are many chemicals on the Prop 65 list that were listed based on questionable animal studies or that were listed as 'known' to cause cancer and reproductive harm but, in fact, they are not known to do that," said Raglin. "These holdings represent some much-needed sanity" for the Prop 65 scheme, he said.
Jeffrey Parker, a partner at law firm Sheppard, said the latest outcome creates a template for future First Amendment challenges. He also noted that the decision by the AG’s office to stipulate an order in this case shows it is "acting rationally and reasonably by recognising that, in similar situations, the result is likely to be the same".
All the same, preparing and litigating a First Amendment challenge is expensive, Parker said, as is defending an alleged Prop 65 violation in court.
As such, "private enforcement actions on any listed chemicals will likely proceed at the same pace unless and until similar injunctive lawsuits are filed and fully litigated", he said.