In Maryland v. Louisiana, 451 U.S. 725, 101 S.Ct. 2114, 68 L.Ed.2d 576 (1981), the Supreme Court reviewed a Louisiana statute that imposed a first-use tax on natural gas extracted from the continental shelf in an amount equivalent to the severance tax imposed on natural gas extracted in Louisiana. See id. at 731, 101 S.Ct. 2114. Taxpayers subject to the first-use tax were entitled to a direct tax credit on any Louisiana Severance Tax owed in connection with the extraction of natural resources within the state. See id. at 732, 101 S.Ct. 2114. Most Louisiana consumers of offshore gas were eligible for tax credits and exemptions, but the tax applied in full to offshore gas moving through and out of state. See id. at 733, 101 S.Ct. 2114. Noting that the state severance tax credit "favored those who both own offshore gas and engage in Louisiana production" and that the "obvious economic effect of this Severance Tax Credit was to encourage natural gas owners involved in the production of offshore gas to invest in mineral exploration and development within Louisiana rather than to invest in further offshore development or in production in other States," the Court held that the statute "unquestionably discriminated against interstate commerce in favor of local interests." Id. at 756 - 57, 101 S.Ct. 2114.