## Facts

- After major oil spills, Congress enacted extensive tanker-safety and pollution-prevention legislation, including the Ports and Waterways Safety Act of 1972 (PWSA) and the Oil Pollution Act of 1990 (OPA), implemented largely through U.S. Coast Guard regulation.
- Washington State created an Office of Marine Safety and directed it to adopt tanker rules providing “best achievable protection” from oil-spill damage.
- Washington promulgated regulations addressing tanker design, equipment, reporting, and operating requirements, including rules on navigation watch procedures, crew English language and training standards, and casualty reporting.
- The International Association of Independent Tanker Owners (INTERTANKO) sued Washington officials, arguing the state regime intruded into a federally controlled area requiring national uniformity, especially for interstate and international shipping.
- The United States intervened, emphasizing federal interests, including foreign affairs implications of inconsistent state tanker requirements.

## Issues

1. Whether federal law (including the PWSA, OPA, and Coast Guard regulations) preempts Washington’s tanker rules governing design, equipment, operating practices, and reporting.
2. Whether Washington may impose broader tanker-safety requirements as part of a “best achievable protection” program, or only narrow rules tied to local conditions that do not conflict with federal regulation.
3. Which specific Washington regulations, if any, are invalid under field preemption and/or conflict preemption principles applicable to maritime safety and commerce.

## Decision

- The Supreme Court unanimously held that several Washington regulations were preempted by the federal tanker-safety and pollution-prevention regime.
- The Court held Washington’s rules on general navigation watch procedures, crew English language skills and training, and maritime casualty reporting were preempted.
- The Court emphasized Congress’s intent for a nationally uniform system administered through federal authority, including the Coast Guard, for key aspects of tanker operation and safety.
- The Court remanded for further consideration of remaining Washington regulations under the clarified preemption analysis, recognizing the substantial federal interest at stake.

## Legal Principles

- When Congress creates a comprehensive, nationally uniform regulatory scheme in a field affecting interstate and international maritime commerce, state laws that add to, differ from, or interfere with that scheme are preempted under the Supremacy Clause.
- Federal maritime regulation can preempt state law through field preemption (federal occupation of the area) and conflict preemption (state measures that obstruct federal objectives or impose inconsistent requirements).
- A federal determination that a vessel meets applicable safety requirements for navigation in U.S. waters overrides inconsistent state determinations.
- States retain limited authority to regulate ports and local waterways only for rules grounded in local conditions (“peculiarities of local waters”) and consistent with federal requirements.

## Conclusion

The Court held that federal statutes and Coast Guard regulations establish a dominant, nationally uniform framework for tanker safety and pollution prevention that preempted Washington’s watchkeeping, crew language/training, and casualty-reporting rules, while leaving only limited room for state regulation tailored to local waters and compatible with federal law.


United States v. Locke, 529 U.S. 89 (2000)