## Facts

- California’s Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65) requires “clear and reasonable” warnings before knowingly exposing individuals to chemicals listed by the state as causing cancer or reproductive toxicity.
- California listed mercury as a chemical known to cause reproductive toxicity.
- Dental amalgam contains mercury; Proposition 65 would therefore require warnings to dental patients about mercury exposure from amalgam.
- The federal Medical Device Amendments of 1976 (MDA) create a comprehensive medical-device regulatory scheme and include an express preemption clause, 21 U.S.C. § 360k(a), barring certain state “requirements” that differ from or add to federal device requirements.
- The FDA had regulations related to “dental mercury,” but had not adopted device-specific requirements or reproductive-toxicity warning requirements for dental amalgam as such.
- Dental amalgam manufacturers sought declaratory relief that Proposition 65’s warning requirement, as applied to amalgam, was preempted by the MDA.
- The district court granted summary judgment for the manufacturers, reasoning that the MDA/FDA scheme was sufficiently specific and that the FDA’s decision not to require reproductive warnings had preemptive effect.
- The State and an intervenor appealed.

## Issues

1. Whether Proposition 65’s warning requirement for mercury exposure from dental amalgam is expressly preempted by 21 U.S.C. § 360k(a) when the FDA has not adopted device-specific requirements or counterpart regulations for dental amalgam.
2. Whether FDA inaction (not requiring a reproductive-toxicity warning) can function as a federal “requirement” that triggers MDA preemption.

## Decision

- The Ninth Circuit reversed the summary judgment for the manufacturers.
- The court held that the MDA did not preempt Proposition 65’s warning requirement as applied to dental amalgam.
- The court concluded that § 360k(a) preemption requires specific, device-applicable federal requirements, which were absent for dental amalgam.
- The court rejected the view that regulatory silence or failure to require a warning constitutes a preemptive federal requirement.

## Legal Principles

- In areas of traditional state police power concerning health and safety, courts apply a presumption against preemption absent clear congressional intent.
- MDA express preemption under 21 U.S.C. § 360k(a) applies only when the FDA has established specific counterpart regulations or other specific federal requirements applicable to the particular device (or device class at issue).
- Regulations governing a component material (e.g., dental mercury) do not, without more, establish device-specific federal requirements for a finished device (e.g., dental amalgam) sufficient to trigger § 360k(a).
- Agency inaction or the absence of a federal warning requirement does not constitute an affirmative federal “requirement” that preempts additional state warning duties under § 360k(a).

## Conclusion

The Ninth Circuit held that California could enforce Proposition 65 warnings for mercury exposure from dental amalgam because the FDA had not imposed device-specific requirements for amalgam, and federal regulatory silence could not supply the affirmative federal requirement necessary for MDA express preemption.


Comm. of Dental Amalgam Alloy Mfrs. & Distribs. v. Stratton, 92 F.3d 807 (9th Cir. 1996)