Chamber of Commerce, et al. v. Environmental Protection Agency, et al.

The decision below raises two important questions about the U.S. Environmental Protection Agency’s (EPA’s) authority to revise a National Ambient Air Quality Standard (NAAQS). Such revisions reset the baseline for a legion of regulations that affect virtually every significant source of the regulated pollutant, and virtually all economic sectors, in the nation. Section 109(d)(1) of the Clean Air Act requires EPA, every five years, to complete a “thorough review” of the latest science before revising a NAAQS, and also allows EPA to act “earlier or more frequently.” This provision requires a thorough review before any revision. But here, EPA claimed for the first time that it can skip that review when it revises a NAAQS between five-year intervals. EPA then confessed error. But the D.C. Circuit upheld the revision—based on a different statutory provision that EPA had not invoked (and even disavowed), and that in any event does not excuse the thorough review. The questions presented are:

1. Whether EPA may revise a NAAQS without the “thorough review” required by section 109(d)(1) simply because it acts “earlier or more frequently” than mandated.

2. Whether EPA must consider costs and attainability when exercising discretion to review and revise a NAAQS “earlier or more frequently” than mandated.