427 U.S. 246 (1976) (U.S. Supreme Court)
Union Electric Co. v.
When reviewing a State Implementation Plan under Clean Air Act §110, must or may EPA consider economic and technological infeasibility as a basis to disapprove a SIP that otherwise meets the statute's enumerated approval criteria, and does the presence of a state variance procedure undermine EPA's approval?
Under Clean Air Act §110(a)(2), EPA shall approve a state implementation plan if it was adopted after reasonable public hearing, includes enforceable emission limitations and other measures necessary to attain and maintain the NAAQS within the statutory time frame, provides for implementation, enforcement, and monitoring, and otherwise meets the Act's specified requirements. Economic and technological feasibility are not among §110's approval criteria. Primary NAAQS under §109(b)(1) are health-based standards with an adequate margin of safety and are not predicated on cost considerations. A SIP that meets §110's criteria must be approved regardless of claims that compliance is infeasible or unduly costly. Any variance, delay, or change to a SIP that would affect attainment or enforceable limits must proceed through the Act's revision and approval mechanisms and cannot be used to undercut the statutory attainment requirements.
EPA is not permitted to consider economic or technological infeasibility in deciding whether to approve a SIP that satisfies §110(a)(2)'s criteria; if those criteria are met, EPA must approve the plan. The existence of a state variance mechanism does not invalidate EPA's approval, but any variance or change that affects attainment or enforceability must be submitted to EPA as a SIP revision and approved in accordance with the Act.
Union Electric is a leading exposition of the Clean Air Act's technology-forcing, health-first architecture and a staple in environmental and administrative law courses. It teaches that: (1) statutory text controls when Congress delineates specific approval criteria; (2) EPA's role in SIP approval is bounded and largely ministerial with respect to enumerated factors; (3) feasibility and cost arguments belong, if at all, in other statutory channels (SIP revisions, compliance orders), not in collateral attacks on SIP approval; and (4) federalism under the Act allows states discretion over means, but not over ends or timing. The case foreshadows and aligns with later holdings that NAAQS are set without consideration of cost and reinforces a disciplined approach to judicial review that respects statutory allocations of authority.