A federal judge in the Eastern District of California has upheld the court’s earlier decision that the state of California cannot require that cancer warning labels be placed on glyphosate-based products under California’s Safe Drinking Water and Toxic Enforcement Act of 1986, commonly known as Proposition 65. The opinion, Nat’l Ass’n of Wheat Growers v. Becerra, No. 2:17-cv-02401 (E.D. Cal.), was issued June 22, 2020 and concludes that it would be a violation of the First Amendment of the United States Constitution to do so.

Proposition 65

The California state law known as Proposition 65 requires the Governor of California to publish a list of chemicals known to the state to cause cancer. The California Office of Environmental Health Hazard Assessment (“OEHHA”) is the state agency with authority to administer Proposition 65 and maintains the list of known carcinogens. As part of that list, OEHHA is required to include any chemical identified by the International Agency for Research on Cancer (“IARC”) identifies as a carcinogen.

Proposition 65 also requires any person in the course of doing business to provide a “clear and reasonable” warning if they knowingly expose another person to one of the chemicals listed as a known carcinogen. Although the text of the statute does not specify what qualifies as a “clear and reasonable” warning, it gives two examples of “safe harbor” warnings which will satisfy the warning requirements of Proposition 65 when placed on products that contain chemicals listed under the statute. Both of these warnings are broad and state that the products on which they are placed are known to cause cancer.


In 2015, IARC issued a report which identified glyphosate as a “probable human carcinogen.” As a result, glyphosate was listed under Proposition 65 and any product containing glyphosate was required to bear a warning label stating that the product was known to cause cancer. Glyphosate is one of the widest used pesticides in the United States. It is the primary ingredient of Roundup, a pesticide developed by Monsanto Company (“Monsanto”), now owned by Bayer. Roundup is registered under the Federal Insecticide, Fungicide, and Rodenticide Act and approved for use on over 100 food crops.

This case was originally filed in 2017 by a coalition of agriculture groups including Monsanto. In the original complaint, the plaintiffs argued that requiring Proposition 65 warning labels to be placed on all products containing glyphosate would violate the United States Constitution. First, the plaintiffs claimed that requiring warning labels to be put on any products containing glyphosate would violate the Free Speech Clause of the First Amendment by compelling speech that is “false and misleading.” Second, the plaintiffs alleged that OEHHA has violated Article VI, Clause 2 of the United States Constitution, commonly known as the Supremacy Clause, which provides that state laws that conflict with federal law are preempted and have no legal effect. The plaintiffs asked the court to issue an injunction, a court order that would prevent required labeling for pesticide products.

In 2018, the court issued such an order. The 2018 order was a preliminary injunction, meaning that the order was issued to maintain the status quo of the issues being litigated. To get a preliminary injunction, a party must show that it will suffer irreparable harm unless the injunction is issued. When making that determination, a court will consider whether the plaintiff is likely to succeed on the merits, whether the plaintiff is likely to suffer irreparable harm without the injunction, whether the balance of equities and hardships is in the plaintiff’s favor, and whether an injunction is in the public interest. In this case, the court felt irreparable harm would take place if manufacturers were required to put Proposition 65 warning labels on glyphosate products before the case was fully resolved.

In its June 22 order, the court has granted a permanent injunction, meaning that the underlying issues have been resolved and glyphosate products will not require Proposition 65 labels going forward.

Court Opinion

In its opinion, the court concluded that requiring glyphosate products to bear Proposition 65 labels was a violation of the First Amendment of the United States Constitution. Although Proposition 65 itself does not violate the First Amendment, the court found that it was unconstitutional as applied to glyphosate.

In reaching this conclusion, the court first noted that the label required by Proposition 65 was “compelled commercial speech.” This means that the labels are speech that is legally required within the realm of commerce. In this case, Proposition 65 would have required any business to provide warnings if they knowingly exposed another person to glyphosate. In the vast majority of cases, the First Amendment prevents the government from either preventing or requiring a private party to make speech. However, the government can compel speech in certain circumstances, such as to protect public healthy and safety. Proposition 65 labels fall into the category of compelled commercial speech that is typically permitted because it protects public health and safety.

When reviewing challenges to Proposition 65 labels, the government has the burden of showing that the commercial speech it was compelling was “purely factual and uncontroversial.” If the government cannot show do so, it must show that the speech is “neither misleading nor connected to unlawful activity.” If the government cannot prove either of those things, then requiring the speech will violate the First Amendment, and may not be compelled.

Here, the court concluded that the Proposition 65 warning labels claiming that glyphosate was a known carcinogen failed both tests. According to the court, it was not factual to state that glyphosate was known to cause cancer when only IARC had identified glyphosate as a “probable human carcinogen.” The court noted that other entities, including the Environmental Protection Agency and the World Health Organization, have concluded that glyphosate does not cause cancer or that there is not enough data to conclude that glyphosate is carcinogenic. Therefore, it would not be “factual” to state that glyphosate is known to cause cancer, failing the first of the government’s tests. The court used the same reasoning to conclude that the government did not meet the second test, and it would be “misleading” to state that glyphosate is known to cause cancer.

Because the government did not meet either test, the court determined that it would be a violation of the First Amendment to require Proposition 65 labels be placed on products containing glyphosate.

Going Forward

Following this decision, glyphosate is not subject to the warning requirements of Proposition 65. This means that anyone doing business in the state of California knowing that they will be exposing others to glyphosate, will not have to provide a warning. That includes a variety of people, ranging from retailers selling Roundup, groundskeeping businesses and those who employ them, and growers selling produce that has been exposed to glyphosate.

At this time, it is unknown whether the defendants will appeal this case. They have 30 days from the date that the judgement is filed in this case to appeal the court’s decision. If they do appeal, they will do so to the Ninth Circuit.

This case does not affect any other litigation involving glyphosate, or any settlement that may be reached in other glyphosate cases.


To read the court’s opinion in Nat’l Ass’n of Wheat Growers v. Becerra, click here.

To read the complaint in Nat’l Ass’n of Wheat Growers v. Becerra, click here.

To read the text of Proposition 65, click here.

For more National Agricultural Law Center resources on pesticides, click here.