## Facts

- North Carolina, through its attorney general, sued the Tennessee Valley Authority (TVA), a federally owned electric utility operating coal-fired power plants in Alabama and Tennessee.
- North Carolina alleged emissions from four TVA plants near the North Carolina border contributed to air pollution and related harms in North Carolina.
- North Carolina pursued state common-law public-nuisance claims, pleading nuisance under North Carolina law and, as applicable, Alabama and Tennessee law.
- After a bench trial, the federal district court held the plants’ emissions constituted a public nuisance and entered an injunction.
- The injunction required TVA to install additional emissions controls and meet tighter emissions limits on an accelerated schedule beyond what existing Clean Air Act (CAA) permits and state implementation plan (SIP) requirements required.

## Issues

1. Whether the Clean Air Act’s comprehensive regulatory and permitting scheme precludes or displaces state common-law public-nuisance claims seeking additional controls on out-of-state, permitted emission sources.
2. Whether a downwind state may use nuisance law to impose its air-quality preferences on sources located in other states.
3. Whether compliance with CAA permits and SIP-based limits bars treating the permitted emissions as a public nuisance and supports vacating an injunction that effectively rewrites regulatory requirements.

## Decision

- The Fourth Circuit vacated the district court’s injunction and remanded with instructions to dismiss the action.
- The court concluded the CAA’s structured framework for regulating interstate air pollution foreclosed North Carolina’s requested nuisance-based relief against TVA’s permitted plants.
- The court held the district court abused its discretion by substituting case-specific nuisance balancing for the CAA’s regulatory mechanisms and by ordering controls and deadlines exceeding those required by permits and the CAA process.
- The court rejected using state nuisance law to override emission standards and compliance determinations made through EPA-approved permitting and SIP programs for sources in other states.

## Legal Principles

- Where the CAA comprehensively regulates emissions from stationary sources through permits and SIPs, state common-law nuisance claims may not be used by a downwind state to impose different emission limits on out-of-state sources.
- Courts should not use open-ended nuisance standards to supplant agency judgments that require technical, cost, feasibility, and policy determinations assigned to EPA and cooperating state regulators under the CAA.
- A source’s compliance with applicable CAA permits and SIP requirements strongly weighs against, and may bar, characterizing the authorized emissions as a public nuisance for purposes of additional injunctive controls.
- The CAA provides designated mechanisms for interstate pollution disputes; state-law remedies that conflict with those mechanisms and outcomes are not available to re-set regulatory obligations through litigation.

## Conclusion

The Fourth Circuit held that North Carolina could not use state public-nuisance law to impose stricter, court-ordered emission controls on TVA’s Alabama and Tennessee plants operating under the Clean Air Act’s permitting regime, and it vacated the injunction and ordered dismissal of the case.


North Carolina ex rel. Cooper v. Tennessee Valley Authority, 615 F.3d 291 (4th Cir. 2010)