In 1984, the Supreme Court issued a unanimous ruling in favor of an Environmental Protection Agency (EPA) rule stemming from the Clean Air Act. The EPA rule allowed states to treat all pollution from a unified industrial group as a singular pollution source for regulatory purposes. A cohort of environmental groups challenged the rule, arguing that it allowed pollution-emitting devices to operate that would not have passed regulatory muster considered on their own.
It was a technical exercise in statutory interpretation—but the case's long-term impact had little to do with pollution or the intricacies of the Clean Air Act. Embedded in that decision, Chevron U.S.A. Inc. v. Natural Resources Defense Council, Inc., was a small revolution in administrative law.
