Page:Michigan v. EPA.pdf/18

 Cite as: 576 U. S. ____ (2015)

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THOMAS, J., concurring

SUPREME COURT OF THE UNITED STATES _________________

Nos. 14–46, 14–47, and 14–49 _________________

MICHIGAN, ET AL., PETITIONERS 14–46 v. ENVIRONMENTAL PROTECTION AGENCY, ET AL. UTILITY AIR REGULATORY GROUP, PETITIONER 14–47 v. ENVIRONMENTAL PROTECTION AGENCY, ET AL. NATIONAL MINING ASSOCIATION, PETITIONER 14–49 v. ENVIRONMENTAL PROTECTION AGENCY, ET AL. ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT [June 29, 2015]

JUSTICE THOMAS, concurring. The Environmental Protection Agency (EPA) asks the Court to defer to its interpretation of the phrase “appropriate and necessary” in §112(n)(1)(A) of the Clean Air Act, 42 U. S. C. §7412. JUSTICE SCALIA’s opinion for the Court demonstrates why EPA’s interpretation deserves no deference under our precedents. I write separately to note that its request for deference raises serious questions about the constitutionality of our broader practice of deferring to agency interpretations of federal statutes. See Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 (1984). Chevron deference is premised on “a presumption that Congress, when it left ambiguity in a statute meant for