Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc.
When a federal statute is ambiguous, should courts defer to a reasonable interpretation of that statute by the federal agency Congress has charged with administering it, even if the court would have read the statute differently?
The Decision
6-0 decision · Opinion by John Paul Stevens · 1984
Majority Opinion— John Paul Stevensconcurring ↓
In a unanimous decision among the six participating justices (6–0), the Supreme Court reversed the D.C. Circuit and upheld the EPA's bubble concept. The opinion was written by Justice John Paul Stevens. Three justices — Thurgood Marshall, William Rehnquist, and Sandra Day O'Connor — took no part in the decision.
The Court's opinion established a landmark two-step framework for determining when courts should defer to an agency's interpretation of a statute it administers. At step one, the court must ask whether Congress has 'directly spoken to the precise question at issue.' If the intent of Congress is clear from the statute's text — that is, if the law is unambiguous — then both the court and the agency must follow Congress's command. The inquiry ends there. But if the court determines that the statute is silent or ambiguous on the specific point, it moves to step two: the court must ask whether the agency's interpretation is based on a 'permissible construction of the statute.' If the agency's reading is reasonable, the court must accept it, even if the court itself would have preferred a different interpretation.
Applying this framework, the Court found that Congress had not directly defined 'stationary source' in a way that resolved the dispute. The term was used differently in various parts of the Clean Air Act, and the legislative history did not reveal a single clear congressional intent on the specific question of whether the bubble concept was permitted or prohibited in non-attainment areas. Because the statute was ambiguous, the Court moved to step two and found that the EPA's plantwide definition was a reasonable policy choice that balanced environmental and economic concerns in a permissible way.
Justice Stevens emphasized that when Congress leaves a gap or ambiguity in a statute, it is effectively delegating authority to the administering agency to fill that gap. Courts are not the appropriate institution to make such policy choices. Judges are generalists who lack the technical expertise agencies bring to regulatory problems. Moreover, agencies are more politically accountable than courts: they operate under the direction of the President, who is elected, whereas federal judges serve for life. When reasonable people could disagree about the best reading of an ambiguous statute, that policy judgment belongs to the agency, not to the judiciary.
The decision thus established a powerful presumption of judicial deference to agency interpretations of ambiguous statutes. This framework — which became universally known as 'Chevron deference' — became one of the most frequently cited and consequential principles in all of American administrative law, shaping how courts reviewed the actions of every federal regulatory agency for decades.
Concurring Opinions
There were no concurring or dissenting opinions. The decision was unanimous among the six justices who participated. Justices Thurgood Marshall, William Rehnquist, and Sandra Day O'Connor recused themselves and took no part in the consideration or decision of the case.
Background & Facts
In 1977, Congress amended the Clean Air Act to impose strict permitting requirements on states that had not yet met national air quality standards. Under these amendments, states were required to establish permit programs regulating new or modified 'stationary sources' of air pollution in areas that had not achieved compliance. The law did not, however, clearly define what counted as a single 'stationary source' of pollution — and that ambiguity became the center of a major legal battle.
The Environmental Protection Agency (EPA), under the Reagan administration in 1981, adopted what became known as the 'bubble concept.' Under this interpretation, an entire industrial plant — a factory, refinery, or manufacturing complex — could be treated as a single 'stationary source' enclosed within an imaginary bubble. This meant that a company could add new pollution-emitting equipment or modify existing equipment without triggering the costly new-source permitting process, so long as the total emissions from the entire plant did not increase. Industry favored this approach because it gave companies flexibility to modernize and grow without navigating burdensome permit requirements for each individual change.
The Natural Resources Defense Council (NRDC), a prominent environmental advocacy organization, challenged the EPA's bubble concept in court. The NRDC argued that Congress intended for each individual piece of pollution-emitting equipment to be treated as its own 'stationary source,' which would require a separate permit review every time a significant new device was added or an old one was modified — even if overall plant emissions stayed the same or decreased. This stricter reading, the NRDC contended, would better serve the Clean Air Act's goal of improving air quality in polluted areas.
The United States Court of Appeals for the District of Columbia Circuit sided with the NRDC, striking down the EPA's bubble concept. The D.C. Circuit found the EPA's interpretation inconsistent with the purposes of the Clean Air Act and held that the agency's plantwide definition of 'stationary source' was impermissible. Chevron U.S.A., Inc., a major oil company that had intervened in the case to support the EPA's regulation, joined the government in petitioning the Supreme Court to reverse the lower court's decision.
The Supreme Court agreed to hear the case because it raised a fundamental question about the relationship between federal courts and the executive-branch agencies tasked with implementing complex regulatory statutes. The justices saw an opportunity to clarify how much deference courts owe to agencies when Congress has left gaps or ambiguities in the laws those agencies administer.
The Arguments
Chevron argued that the EPA's plantwide definition of 'stationary source' — the bubble concept — was a reasonable and permissible interpretation of an ambiguous term in the Clean Air Act. Because Congress did not clearly define the term, the EPA was entitled to exercise its expert judgment in choosing among plausible readings of the statute.
- The Clean Air Act did not contain a single, fixed definition of 'stationary source,' and Congress used the term in different ways in different parts of the law, demonstrating that the term was genuinely ambiguous.
- The EPA's bubble concept served legitimate policy goals by giving industry flexibility to allocate pollution reductions in the most cost-effective way, which was consistent with the broader purposes of the statute.
- Federal agencies like the EPA possess specialized expertise in environmental regulation and are politically accountable through the executive branch, making them better suited than courts to resolve policy ambiguities in complex regulatory statutes.
The NRDC argued that the Clean Air Act's permit program for non-attainment areas was designed to force meaningful review of each new pollution source, and the EPA's bubble concept undermined that goal by allowing companies to avoid permit requirements. The D.C. Circuit was right to reject the EPA's interpretation because it conflicted with Congress's intent to improve air quality.
- The legislative history and structure of the 1977 Clean Air Act amendments showed that Congress intended the non-attainment program to require rigorous, source-by-source review to ensure progress toward meeting air quality standards.
- The EPA's plantwide definition would allow companies to add significant new sources of pollution without any permit review at all, effectively gutting the statutory program for the most polluted areas of the country.
- Courts have an independent duty to interpret statutes and should not simply rubber-stamp an agency's reading of the law, especially when the agency's interpretation changed with a new presidential administration and appeared to be driven by political rather than scientific considerations.
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