Skip to content

What are My Defenses in a Prop 65 Lawsuit?

Proposition 65 requires businesses to provide “clear and reasonable” warnings prior to exposing individuals to listed chemicals. Violations of this warning requirement are redressed exclusively through civil lawsuits. A plaintiff who can demonstrate that an entity failed to provide warnings in compliance with the statute may seek civil penalties (of which 25% is paid to the plaintiff), injunctive relief, and payment of costs and attorney’s fees. Because of the ease with which a plaintiff can bring a Proposition 65 lawsuit and the high potential payout for plaintiffs and their attorneys, defendants who are lax in compliance can face significant penalties. Businesses must be familiar with the requirements of the legislation to be prepared to defend against enforcement lawsuits.

Does My Company Employ Less Than 10 Employees?

Proposition 65 applies only to “persons in the course of doing business,” which excludes business that employ less than 10 employees. Typically, this is proven via tax records. However, private enforcers are becoming increasingly aggressive about how businesses prove this statutory exclusion, arguing, for example, that independent contractors have been misclassified.

Even if a business can successfully prove that the statutory exclusion applies to it, it still may have to answer to business customers who are being sued and who employ 10 or more employees. In these circumstances, most small businesses who otherwise qualify for the exclusion take the lead on resolving the claim in order maintain good business relations with their customers. The exclusion is swallowed up by business realities.

Did Plaintiff Comply with the 60 Day-Notice Requirement?

A private enforcer must comply with a 60-day notice requirement to obtain standing to bring a Proposition 65 action. The notice must strictly comply with the provisions outlined in the statute and related regulations, which includes providing a copy of the statute, a summary of the violation, the list of chemicals implicated in the violation, and the route of exposure, among other information. Plaintiffs are prohibited from filing a complaint until after the expiration of the 60-day notice period, and can pursue the action only if no other enforcement body has begun prosecuting the case. A business receiving such a notice should examine it closely to ascertain if any deviations from the notice requirements can be used as a basis to dismiss the action.

Can My Company Use the “Safe Harbor” Defense?

Not all “exposures” to listed chemicals require a warning, only those exceeding the regulatory level specified for the chemical. That is, warnings are not required if the defendant company can demonstrate that: (i) for listed carcinogens, the exposure is below the no significant risk level, i.e., does not pose a significant risk of cancer assuming that the individual is exposed to the chemical over a 70-year lifetime; and (ii) for reproductive toxicants, the exposure is below the maximum acceptable dose level, which is 1/1000th of the no observable effect level for the chemical. Thus, a business facing a Proposition 65 claim should consider undertaking an exposure assessment to determine whether exposures to the listed chemical at issue in the claim are below these levels. However, this defense presents a difficult threshold for defendants: employing experts and conducting testing to make these determinations can be extremely costly and time consuming. Further, plaintiffs can, and do, challenge every aspect of these exposure assessments, creating a factual dispute requiring experts to testify about and a court to decide upon.

Is the Chemical “Naturally Occurring”?

An assertion that the chemical is “naturally occurring” can serve as a defense in enforcement actions involving foods. This defense pertains to food products and dietary supplements which may contain chemicals that are generated from naturally occurring processes. For example, lead and other heavy metals may be naturally taken up by plants, which in turn are then processed into food products. But the Proposition 65 “naturally occurring” defense imposes a high, strict bar on its proof, and it is a rare situation where a defendant can prove all of its required elements.

Grimaldi Law Offices has been advising clients for over 20 years on chemical and product law. For knowledgeable advice and in-depth analysis on your Prop 65 compliance obligations, contact Grimaldi Law Offices at (415) 463-5186 or email us at [email protected].

This is attorney advertising. Please see disclaimer.


Ms. Grimaldi maintains a diverse environmental law practice focusing on chemical and product regulation and litigation defense. Her practice areas include Proposition 65, California's Safer Consumer Products Regulations, California's Rigid Plastic Packaging Container Act and the federal Toxic Substances Control Act. Ms. Grimaldi graduated from the University of California Hastings College of the Law magna cum laude and holds a Bachelor of Science Degree in Bacteriology from University of California, Davis. Prior to attending law school, she worked as a research assistant in laboratories at the University of California, San Francisco Cancer Research Institute and at the University of California, San Francisco School of Medicine.