Chevron U.S.A.

, Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837 (1984)

IRAC Summary

Issue: The central issue in Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc. is whether a court should defer to an administrative agency’s interpretation of a statute that it administers if the statute is ambiguous and the agency’s interpretation is reasonable.

Rule: The Supreme Court established the “Chevron deference,” a legal principle that courts must defer to administrative agencies’ interpretation of ambiguous statutes that they are responsible for administering, provided that the interpretation is reasonable.

Application: The Environmental Protection Agency (EPA) interpreted an ambiguous provision of the Clean Air Act regarding the permitting of “stationary sources” of pollution in a way that allowed states to treat all pollution-emitting devices within the same industrial grouping as a single “source.” The Natural Resources Defense Council (NRDC) argued that this interpretation was not permissible under the Act. The Supreme Court applied the two-step Chevron framework, first asking whether Congress had directly spoken to the precise question at issue, and finding that it had not. Then, the Court considered whether the EPA’s interpretation was based on a permissible construction of the statute, and found that it was.

Conclusion: The Supreme Court held that the EPA’s interpretation of the Clean Air Act was entitled to deference and was a permissible construction of the statute, thereby upholding the EPA’s policy.

Detailed IRAC Outline


The detailed issue involves the scope of the EPA’s authority to define the term “source” under the Clean Air Act amendments of 1977. Specifically, whether the EPA’s “bubble policy,” which permits an existing plant that contains several pollution-emitting devices to install or modify one piece of equipment without meeting the permit requirements for new sources, so long as the total emissions from the plant do not increase, is a correct interpretation of the Clean Air Act.


Chevron v. NRDC established a two-step framework for courts to apply when reviewing an agency’s interpretation of a statute:

  1. If the statute is clear and unambiguous, then the court must give effect to the intent of Congress.
  2. If the statute is ambiguous or silent on the issue, the court must determine if the agency’s interpretation is based on a permissible construction of the statute; if yes, the court should defer to the agency.


  1. Chevron Step One: The Court examined the Clean Air Act and found that Congress did not provide a clear definition of the term “source.” Since the statute was silent or ambiguous, the Court proceeded to Chevron Step Two.

  2. Chevron Step Two: The Court considered whether the EPA’s “bubble policy” was a permissible interpretation of the Clean Air Act. The Court recognized that the EPA, as the agency charged with administering the statute, has the authority to fill in the gaps left by Congress. The Court evaluated the reasonableness of the EPA’s interpretation, taking into account the technical expertise of the agency, the complex nature of the Clean Air Act, and the legislative history.


After applying the Chevron two-step analysis, the Court concluded that the EPA’s definition of “source” was based on a permissible and reasonable interpretation of an ambiguous provision in the Clean Air Act. The “bubble policy” was therefore upheld, and the Chevron deference doctrine was solidified, instructing future courts to defer to agencies’ interpretations of ambiguous statutes within their purview, as long as those interpretations are reasonable.

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