Michigan v. Envtl. Prot. Agency
The Court ruled that the EPA acted unreasonably when it decided power plants should be regulated for toxic air emissions without ever considering how much that regulation would cost.
The decision means federal agencies generally cannot claim a law lets them ignore costs entirely when deciding whether regulation is 'appropriate,' reinforcing that cost is a factor agencies must weigh even when a statute does not say so explicitly.
“One would not say that it is even rational, never mind "appropriate," to impose billions of dollars in economic costs in return for a few dollars in health or environmental benefits.”
The majority's core reasoning for why cost must factor into the EPA's decision.
How it got here: The D.C. Circuit upheld the EPA's refusal to consider cost, and the states and industry groups asked the Supreme Court to review that ruling.
The Case in Depth
What happened
The EPA decided that coal- and oil-fired power plants should be regulated for emissions of mercury and other hazardous air pollutants, finding that doing so was "appropriate and necessary." The agency refused to weigh the cost of compliance in making that decision, even though it later estimated the rule would cost power plants $9.6 billion a year while quantifiable health benefits were only $4 to $6 million a year. Twenty-three states and industry groups challenged the EPA's refusal to consider cost.
The question before the Court
Did the EPA act reasonably when it refused to think about cost at all in deciding whether to regulate power plants' toxic air emissions?
The Court's answer
No — the Court ruled that the EPA acted unreasonably when it decided power-plant regulation was "appropriate and necessary" without giving any thought to cost. Even under the deferential Chevron standard, which lets agencies fill gaps in ambiguous statutes, the EPA strayed too far by treating cost as entirely irrelevant to its threshold decision, especially since compliance costs ran to about $9.6 billion a year against only $4 to $6 million in quantifiable health benefits.
The Court held that the phrase "appropriate and necessary" is broad enough to require at least some attention to cost, and that a related provision requiring a study of costs reinforced that reading. It did not require a formal cost-benefit analysis, leaving it to the EPA to decide, within reasonable limits, how to factor cost into its finding going forward.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
The ruling sent the EPA's mercury and air toxics rule for power plants back for further proceedings, forcing the agency to redo its cost analysis before regulation could stand. More broadly, agencies across government now have less room to dismiss cost as irrelevant when a statute asks them to decide what regulation is 'appropriate,' affecting how future environmental and other rules get written and defended in court.
What changes now
The case goes back to the D.C. Circuit and then to the EPA for further proceedings consistent with the Court's ruling. The EPA must now factor cost into its threshold decision about regulating power plants' hazardous air pollutant emissions, though the Court left it to the agency to decide how much weight to give cost and whether a formal cost-benefit analysis is required. This is a final decision on the merits, not a temporary order.
What this does not decide
The Court did not require the EPA to conduct a formal, monetized cost-benefit analysis before finding regulation appropriate and necessary. It left it up to the agency, within the bounds of reasonable interpretation, to decide how to account for cost, and did not resolve whether the EPA could rely on ancillary benefits it had not actually considered when making its original finding.
Concurrences and dissents
Concurrence — Justice Thomas
Justice Thomas agreed that the EPA's interpretation deserved no deference, but wrote separately to question whether Chevron deference itself is constitutional. He argued that letting agencies effectively make policy judgments with the force of law under the guise of statutory interpretation raises serious separation-of-powers problems under Article I and Article III.
Dissent — Justice Kagan
“That is a peculiarly blinkered way for a court to assess the lawfulness of an agency's rulemaking.”Kagan's central objection to the majority's narrow focus on a single stage of EPA's rulemaking.
Justice Kagan argued that the EPA did consider costs extensively, just not at the very first step of its multi-stage regulatory process, and that this was a reasonable way to structure a complex rulemaking. She noted the EPA's own cost-benefit study found benefits exceeding costs by three to nine times, and would have upheld the rule because Congress left it to the agency's discretion how and when to weigh costs.
How the Court got there
The legal reasoning, step by step
- The Court applied the Chevron framework, which requires courts to accept an agency's reasonable reading of an ambiguous statute it administers, but said agencies must still stay within the bounds of reasonable interpretation.
- The Court read the phrase 'appropriate and necessary' as a broad, all-encompassing standard that, read naturally, requires at least some attention to cost, reasoning that it is not rational to impose billions of dollars in costs for only a few dollars of benefit.
- The Court found support in the statute's structure: Congress required a separate mercury study that explicitly considered costs, showing that cost was part of the framework the agency itself said governed its appropriate-and-necessary finding.
- The Court rejected the EPA's arguments that other provisions' express mentions of cost implied cost was irrelevant here, that a later opportunity to consider cost excused ignoring it at the threshold, and that treating power plants like other sources required ignoring cost, noting Congress deliberately wrote a different, more expansive standard for power plants.
- Because the EPA gave cost no consideration at all when making its threshold finding, the Court concluded that interpretation fell outside the bounds of reasonable statutory interpretation, even under Chevron's deferential standard.
Doctrinal impact
Cases affected by this decision
Distinguishes Whitman v. American Trucking Assns., Inc. (531 U. S. 457)
The Court said this case's rule against implying cost consideration doesn't apply because 'appropriate and necessary' is a far broader standard.