Ohio v. Environmental Protection Agency Revisions: 6/27/24
The Supreme Court blocked enforcement of the EPA's 'Good Neighbor Plan' — a major rule requiring upwind states to limit ozone-forming industrial emissions — while an appeal proceeds, finding that the agency likely failed to explain how its plan remained valid after courts removed more than half the states it was built around.
The 5-4 decision is a temporary pause, not a final ruling on the rule's legality, but it frees factories and power plants in the remaining covered states from complying during what could be years of further litigation — and leaves downwind communities without that protection in the meantime.
How it got here: States and industry groups asked the D.C. Circuit to pause the EPA rule while they appealed; the D.C. Circuit refused; they then brought emergency stay applications to the Supreme Court.
The Case in Depth
What happened
The EPA tightened national ozone pollution standards in 2015 and, years later, rejected the cleanup plans of more than 20 upwind states, finding that pollution from those states drifted downwind and harmed neighboring states' air quality. In place of those rejected state plans, EPA imposed a single federal rule — the Good Neighbor Plan — requiring industrial facilities in all 23 targeted states to adopt cost-effective emissions controls. But before the rule took full effect, courts blocked it from applying to 12 of those states, covering more than 70 percent of the pollution EPA had intended to address. The remaining covered states and industry groups argued that a rule designed for 23 states could not simply be applied unchanged to a much smaller group.
The question before the Court
Can states and companies force a pause on a federal EPA air-pollution rule when courts had already blocked that rule from applying to more than half the states it was originally designed to cover — leaving open whether the rule still made sense for the smaller group that remained?
The Court's answer
Yes — the Court paused the EPA's Good Neighbor Plan, ruling that the states and companies challenging it were likely to win in the long run because EPA probably acted unreasonably in keeping the rule intact after so many states dropped out.
EPA built its emissions-control plan around a cost-effectiveness analysis that assumed all 23 targeted states would participate. When courts blocked the rule from applying to 12 of those states — more than 70 percent of the emissions the plan was designed to address — EPA kept the rule running unchanged, relying on a "severability" clause. But that clause simply declared the plan would continue no matter how many states remained; it never explained whether the same emissions controls still made sense for a much smaller and different group of states. EPA could not even confirm at oral argument that its analysis would have produced the same results for fewer states. Because EPA ignored this important problem without a reasoned explanation, the challengers showed a sufficient likelihood of winning their case in court.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Industrial facilities in the states still subject to the rule — including power plants and factories — won't have to install or operate costly emissions controls during the appeal. Communities in downwind states that receive ozone pollution drifting across state lines may face continued health risks from that pollution while the legal fight plays out, potentially for several years.
What changes now
The Good Neighbor Plan is paused as to the applicant states and industry groups while their appeal proceeds in the D.C. Circuit. If that court strikes the rule down, EPA would have to start over or revise the plan. If EPA wins, enforcement would resume. Separately, litigation continues in multiple courts over whether EPA was right to reject the original state plans — those outcomes could change which states the federal rule covers. The Supreme Court stay automatically ends if the D.C. Circuit appeal concludes without a petition for Supreme Court review being timely filed.
What this does not decide
The Court does not decide whether the Good Neighbor Plan is ultimately unlawful — only that the challengers are likely enough to win that enforcement should pause during the appeal. The Court also declined to address the applicants' other arguments for why the rule might be invalid, and it does not resolve the separate litigation over whether EPA was right to reject each state's original air-quality plan.
Concurrences and dissents
Dissent — Justice Barrett
Justice Barrett argued the majority granted emergency relief based on a theory that barely appeared in the applicants' briefs and faced serious procedural and substantive obstacles. She contended that the Clean Air Act's procedural rules likely barred the challengers from raising this objection in court at all. On the merits, she argued that EPA's methodology for setting emissions limits relied on nationwide industry data rather than state-specific inputs, so fewer states in the plan would not have changed the emissions obligations — a point EPA later confirmed by denying petitions for reconsideration. She also argued that any failure to explain the plan more fully was harmless under the Clean Air Act's stringent harmless-error rule, and that the challengers admitted they could not say whether the analysis would actually differ for fewer states.
How the Court got there
The legal reasoning, step by step
- The Court applied the standard four-factor test for emergency stays, weighing: likelihood of winning the underlying lawsuit, risk of serious harm without the pause, harm to the other side from granting the pause, and the broader public interest. Because both sides had strong arguments on the last three factors — EPA cited air-quality benefits for downwind states, while the remaining states cited sovereignty concerns and hundreds of millions to billions of dollars in non-recoverable compliance costs — the outcome turned entirely on the first factor: who was likely to prevail.
- Under the 'arbitrary-and-capricious' standard — the legal test for whether an agency acted unreasonably — an agency must provide a satisfactory explanation for its choices, must show a rational connection between the facts it found and the action it took, and cannot simply ignore 'an important aspect of the problem.' If it fails any of those requirements, a court can reverse the rule.
- EPA's plan determined which emissions controls were cost-effective by finding the 'knee in the curve' — the point at which further spending by upwind states produces little additional improvement in downwind air quality. That calculation was done collectively for all 23 targeted states, assuming all of them would participate. Commenters warned during the public process that if some states dropped out, the mix of industries and existing pollution controls would change, and the knee in the curve might shift — meaning the same emissions mandates might no longer maximize cost-effective improvements.
- EPA's only formal response to that concern was a severability clause declaring the plan would 'continue to be implemented' regardless of how many states remained — even if just one state were left. But a severability clause says nothing about whether the underlying analysis still holds for a smaller group of states. At oral argument, the government acknowledged it could not say with certainty that the cost-effectiveness analysis would yield the same results if applied to a fraction of the original states.
- EPA's three alternative defenses all failed. First, the severability clause showed awareness of the problem but sidestepped it rather than answering it. Second, EPA's claim that the concern was never raised during public comment was rejected — commenters did alert EPA that dropping states from the plan might require a new assessment, and EPA's own actions confirmed it was aware of the issue. Third, nothing required the applicants to go back to EPA and ask for an explanation a second time when EPA already had a chance to address the concern and chose not to.