Ohio v. EPA

Supreme Court of the United States · 2024 · Administrative Law

603 U.S. 279 (2024)

Updated August 1, 2026

Administrative Lawreasoned response to commentsAPAarbitrary and capriciousreasoned decisionmakingnotice and commentsignificant commentsState Farm

Facts

EPA revised ozone standards in 2015, which required States to submit new State Implementation Plans addressing, among other things, the Clean Air Act's Good Neighbor Provision. EPA proposed to disapprove more than 20 SIPs and, during the comment period, proposed a single FIP covering 23 States based on the assumption that all covered States would be subject to a uniform set of emissions-control measures chosen to maximize cost-effective downwind ozone improvements. Commenters warned that if some States were excluded because the SIP disapprovals failed, EPA would need to reassess whether the same measures still maximized cost-effectiveness for the remaining States. EPA issued the final FIP with a severability provision but did not explain whether or why the same controls remained justified after courts stayed 12 SIP disapprovals, removing over 70 percent of the emissions EPA originally planned to regulate through the FIP.

Issue

Whether the applicants were likely to succeed on their claim that EPA acted arbitrarily or capriciously by enforcing the final FIP against the remaining States after many originally covered States dropped out, without giving a reasoned response to comments questioning whether the rule's cost-effectiveness analysis still held. Also, whether that likelihood justified a stay pending judicial review.

Rule

For a stay, the Court considers likelihood of success on the merits, irreparable injury, injury to others, and the public interest. On the merits, agency action is arbitrary or capricious if it is not reasonable and reasonably explained; the agency must provide a satisfactory explanation with a rational connection between the facts found and the choice made, and it may not ignore an important aspect of the problem. Under the Clean Air Act's reasonable-specificity requirement, a party need not present the identical argument later made in court so long as the agency had notice of the objection in substance during the comment period.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

The Federal Transit Safety Bureau proposed a rule requiring rail yards in 14 states to install a uniform braking-monitoring system at a single cost threshold. The agency's proposal explained that the threshold was chosen because it maximized safety gains per dollar when all 14 states were covered. During notice and comment, several state transportation departments warned that if pending litigation removed a large number of states from the rule, the cost-effectiveness calculation might change, but the final rule did not address that point.

If a court reviews the final rule under arbitrary-and-capricious review, which is the strongest argument for setting it aside?

Explanation. The majority held that agency action is arbitrary or capricious when it is not reasonable and reasonably explained, including when the agency ignores an important aspect of the problem or fails to give a reasoned response to a significant comment. Where the rule's justification assumed participation by all covered jurisdictions, and commenters specifically warned that a materially smaller set might alter the cost-effectiveness analysis, the agency must explain whether and why the same controls remain justified. It need not be shown that the threshold is definitely wrong; the explanatory failure itself is the problem.