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WYOMING v. OKLAHOMA Opinion of the Court

one, but many or every, State adopted similar legislation.” Healy v. Beer Institute, 491 U. S. 324, 336 (1989). Because of the nature of Wyoming’s claim, and the absence of any other pending litigation involving the same parties or issues, we find the present case appropriate for the exercise of this Court’s original jurisdiction. Accordingly, we accept the recommendation of the Special Master that Wyoming should be permitted to bring this action, and we reject Oklahoma’s exceptions to the Special Master’s Report. III We also agree with the Special Master’s ultimate conclusion that the Act is invalid under the Commerce Clause. The Commerce Clause of the United States Constitution provides that “[t]he Congress shall have Power. . . [t]o regulate Commerce. . . among the several States. . . .” Art. I, § 8, cl. 3. It is long established that, while a literal reading evinces a grant of power to Congress, the Commerce Clause also directly limits the power of the States to discriminate against interstate commerce. See New Energy Co. of Indiana v. Limbach, 486 U. S. 269, 273 (1988) (citing Hughes v. Oklahoma, 441 U. S. 322, 326 (1979); H. P. Hood & Sons, Inc. v. Du Mond, 336 U. S. 525, 534–535 (1949); Welton v. Missouri, 91 U. S. 275 (1876)). “This ‘negative’ aspect of the Commerce Clause prohibits economic protectionism—that is, regulatory measures designed to benefit in-state economic interests by burdening out-of-state competitors.” New Energy Co., supra, at 273–274; see also Bacchus Imports, Ltd. v. Dias, 468 U. S. 263, 270–273 (1984); H. P. Hood & Sons, supra, at 532–533. When a state statute clearly discriminates against interstate commerce, it will be struck down, see, e. g., New Energy Co., supra, unless the discrimination is demonstrably justified by a valid factor unrelated to economic protectionism, see, e. g., Maine v. Taylor, 477 U. S. 131 (1986). Indeed, when the state statute amounts to simple economic protectionism, a “virtually per se rule of invalidity”