## Facts

- Oakland and San Francisco sued several major fossil-fuel producers in California state court in 2017, asserting California public nuisance theories tied to climate-change harms and sea-level rise.
- The cities sought an abatement fund to finance adaptation measures, including coastal infrastructure.
- Defendants removed the actions to federal court, asserting multiple jurisdictional grounds, including federal-question jurisdiction under 28 U.S.C. § 1331 based on federal common law.
- The district court denied remand, concluding the claims were necessarily governed by federal common law.
- After removal, the cities amended to add an explicit federal common-law public nuisance claim while continuing to contest removal.
- The district court dismissed the federal common-law claim under Rule 12(b)(6), reasoning the claims were not judicially manageable and were displaced by the Clean Air Act and EPA regulation.
- The cities appealed, challenging both the denial of remand and the dismissal.

## Issues

1. Whether the cities’ original state-law public nuisance complaints “arose under” federal law for purposes of removal under 28 U.S.C. § 1331.
2. Whether any exception to the well-pleaded complaint rule (including substantial federal question or complete preemption/artful pleading) supported federal-question jurisdiction.
3. Whether the cities’ post-removal amendment adding a federal claim and the district court’s Rule 12(b)(6) dismissal barred appellate review of the earlier denial of remand.

## Decision

- The Ninth Circuit vacated the district court’s judgment and its order denying remand.
- The court held the original state-law nuisance claims did not “arise under” federal law for § 1331 purposes, and federal-question jurisdiction could not support removal.
- The court rejected reliance on the substantial-federal-question doctrine and rejected complete preemption as a basis to treat the state-law claims as inherently federal.
- The court held the post-removal addition of a federal claim cured any jurisdictional defect for subsequent proceedings, but a Rule 12(b)(6) dismissal generally does not foreclose appellate review of an erroneous denial of remand.
- The case was remanded for the district court to consider other asserted bases for federal jurisdiction (separate from § 1331).

## Legal Principles

- Under the well-pleaded complaint rule, federal-question jurisdiction exists only when a federal issue appears on the face of a properly pleaded complaint.
- A state-law claim does not “arise under” federal law merely because federal law may become relevant as a defense or may later be consulted in adjudicating the claim.
- The substantial-federal-question doctrine applies only when a state-law claim necessarily raises a federal issue that is actually disputed, substantial to the federal system as a whole, and consistent with the federal-state judicial balance.
- Complete preemption is rare and requires clear congressional intent that a federal statute provide the exclusive cause of action; federal common law, standing alone, does not establish complete preemption for removal.
- Post-removal amendments may affect ongoing jurisdiction, but a dismissal for failure to state a claim typically does not prevent appellate review of a prior improper refusal to remand.

## Conclusion

The Ninth Circuit concluded that Oakland’s and San Francisco’s state-law climate nuisance complaints were not removable on federal-question grounds, vacated the federal court’s merits dismissal and remand denial, and returned the case for evaluation of any alternative jurisdictional bases for removal.


City of Oakland v. BP PLC, 969 F.3d 895 (9th Cir. 2020)