In the case's hearing of evidence, it is said that Louisiana's purpose of the tax was to pay back the citizens of Louisiana who were affected by the damages to the state's coastal regions, as well as compensating citizens for the costs that the state paid to protect those resources.

The favor ruled that Louisiana unconstitutionally used its "first-use" tax on natural gases and violated the Commerce Clause of the United States Constitution which says that Congress has the power to regulate commerce with foreign nations, several states, and even Indian Tribes.

Aftermath: Post ruling of the court, Louisiana had to stop its "first-use" tax, and it caused the Supremacy Clause from the Constitution to be reinforced as an example for the future.

The court said the Natural Gas Act was violated by the taxing that took place and affirmed the Supremacy Clauses status with that decision.

Text of Maryland v. Louisiana, 451 U.S. 725 (1981) is available from: Justia Library of Congress Oyez (oral argument audio)