Alaska Department of Environmental Conservation v. Environmental Protection Agency
The Supreme Court ruled that the EPA can step in and block construction of a pollution-emitting facility when it finds a state's pollution-control decision was not reasonably justified, even though the state agency has primary responsibility for making that call.
The decision upholds EPA orders that stopped a zinc mine's expansion in Alaska after the state agency accepted a weaker pollution-control technology without adequately explaining why a stronger, proven option was too costly, reinforcing federal oversight of state clean-air permitting decisions.
“It would be unusual, to say the least, for Congress to remit a federal agency enforcing federal law solely to state court.”
Rejecting Alaska's argument that EPA could only challenge state permits in state court.
How it got here: The EPA issued orders blocking the state-approved permit; Alaska and the mine sought review in the Ninth Circuit, which upheld EPA's authority and orders, and the Supreme Court then took the case.
The Case in Depth
What happened
A zinc mine in remote northwest Alaska sought to expand production, which required a new state permit specifying the "best available control technology" to limit nitrogen oxide emissions from its generators. Alaska's environmental agency initially found a stronger technology (SCR) was feasible, but ultimately approved a weaker, cheaper alternative (Low NOx) after the mining company objected to the cost.
The question before the Court
Could the EPA block a mining company's new power generator because it disagreed with Alaska's choice of pollution-control technology for the permit?
The Court's answer
No — the Court ruled that the EPA does have authority to block construction when a state's pollution-control decision is not reasonably justified, even though the state agency makes the first call. The Clean Air Act's PSD program requires states to select technology achieving the "maximum" feasible pollution reduction, and the Court found this constrains state discretion enough that EPA can act as a check when a state's reasoning doesn't hold up.
Applying that standard here, the Court found EPA was right to object: Alaska's agency first found a stronger pollution control technology economically feasible, then reversed itself without new evidence, ultimately picking a weaker option mainly to support the mine's expansion project. Because the state's own record contradicted its final decision, EPA's finding that the choice was unreasoned survived review, and the mine's construction was properly blocked until better justification was provided.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Companies seeking permits to build or expand pollution-emitting facilities can no longer assume a state's technology choice is the last word — the EPA can override it if the state's reasoning doesn't hold up. States must now build a solid, well-documented record justifying their pollution-control choices to withstand federal review.
What changes now
The ruling is final on the legal question of EPA's authority, but it leaves Alaska free to revisit its technology decision and build a proper record to justify a weaker control option if it can. By the time of the decision, Alaska had already issued a new permit requiring the stronger technology, contingent on the outcome of this case, so the mine's construction plans and any future permitting will proceed under the confirmed framework of federal oversight.
What this does not decide
The Court did not decide what the "correct" pollution-control technology should be for this mine — it only addressed whether EPA can check that a state's decision was reasonably justified. The opinion also stresses this involved preconstruction orders, not an EPA veto imposed long after construction was complete.
Concurrences and dissents
Dissent — Justice Kennedy
“The majority creates a sort of Zeno's paradox for state agencies.”Warning that states could never achieve finality if EPA can always demand more justification.
Justice Kennedy argued the statute gives states, not EPA, the final word on BACT determinations once a state has followed the required procedures and weighed the statutory factors. He would have held that EPA's enforcement authority applies only when a state violates an actual Act requirement, not merely reaches a different substantive judgment, and warned the majority's approach undermines state authority, disrupts burden-of-proof rules, and could even let EPA override state court rulings.
How the Court got there
The legal reasoning, step by step
- The Court read the Clean Air Act's enforcement provisions together with its definition of 'best available control technology' (BACT), concluding that Congress gave the EPA broad authority to stop construction when a state's compliance with any Act requirement, including a properly justified BACT choice, is lacking.
- Because the BACT definition requires the 'maximum' achievable pollution reduction after weighing costs and other factors, the Court held this language limits — rather than eliminates — a state's discretion, meaning a state's technology pick must be reasonable and explained, not just present in the permit.
- Applying deference principles for longstanding agency interpretations that fall short of the strongest form of deference, the Court found EPA's view — that it may check unreasonable state BACT calls without dictating the correct answer — was a permissible reading of an ambiguous statute.
- The Court rejected Alaska's argument that review of BACT determinations must happen only in state courts, reasoning that Congress does not lightly route federal enforcement exclusively through state judicial systems, and nothing in the statute's text supported that limit.
- Turning to the facts, the Court applied ordinary arbitrary-and-capricious review and found the state agency's own record showed inconsistent, unsupported reasoning — first calling the stronger technology economically feasible, then reversing course without new evidence — so EPA's finding that the state's choice was unreasoned was itself not arbitrary.