## Facts

- Missouri adopted a Clean Air Act state implementation plan (SIP) with stringent sulfur-dioxide emission limits for the St. Louis area.
- The Environmental Protection Agency (EPA) approved Missouri’s SIP under Clean Air Act § 110(a)(2).
- Union Electric Company operated coal-fired plants subject to the SIP’s sulfur-dioxide limits.
- Union Electric did not seek judicial review within 30 days of EPA’s approval; instead, it obtained one-year variances from state and county agencies.
- While Union Electric sought extensions of its variances, EPA notified it that its emissions violated the SIP.
- Union Electric then petitioned the Eighth Circuit to review EPA’s SIP approval, asserting that economic and technological difficulties arising more than 30 days after approval made compliance impossible.
- The Eighth Circuit dismissed for lack of jurisdiction, concluding that infeasibility is not a valid basis to overturn SIP approval.

## Issues

1. Whether EPA may consider economic and technological infeasibility in deciding whether to approve or disapprove a SIP under Clean Air Act § 110(a)(2).
2. Whether a petition under Clean Air Act § 307(b)(1), filed after the 30-day review period based on “grounds arising after,” may challenge a SIP approval on later-arising claims of economic or technological infeasibility.

## Decision

- The Supreme Court affirmed the Eighth Circuit’s dismissal.
- EPA’s SIP-approval inquiry under § 110(a)(2) is confined to the statute’s enumerated criteria; economic and technological infeasibility is not among them.
- Because infeasibility could not justify EPA’s disapproval of a SIP that satisfies § 110(a)(2), it cannot support judicial invalidation of EPA’s approval at any time.
- The “grounds arising after” clause in § 307(b)(1) does not permit reopening SIP approvals based on post-approval claims of infeasibility.

## Legal Principles

- Under Clean Air Act § 110(a)(2), the EPA Administrator must approve a SIP that was adopted after notice and hearing and meets the statute’s specified requirements.
- Statutory deadlines for attainment of primary and secondary ambient air quality standards are not conditioned on source-specific economic or technological feasibility.
- Judicial review under § 307(b)(1) is limited to objections that, if they had been before EPA at the time of approval, could have required disapproval under the statutory criteria; feasibility objections fall outside that scope.
- The Clean Air Act’s structure assigns States primary responsibility to craft SIP measures; EPA’s role is to assess statutory compliance, not to balance costs against health-based air quality requirements.

## Conclusion

The Court held that economic and technological infeasibility is irrelevant to EPA’s approval of a SIP that meets Clean Air Act § 110(a)(2) criteria, and that § 307(b)(1) does not authorize late challenges to SIP approvals on post-approval infeasibility grounds.


Union Elec. Co. v. EPA, 427 U.S. 246 (1976)