The United States v. Louisiana et al., also known as the Louisiana Boundary Case, was a Supreme Court case in 1968 that addressed a dispute over submerged lands and their associated mineral rights off the coast of Louisiana. The State of Louisiana claimed ownership based on its historical boundaries while the federal government argued it held control due to its authority over coastal waters under international law. The court ruled in favor of the U.S. federal government, stating that it had paramount rights to explore, exploit and conserve natural resources beneath navigable waters seaward from low-water mark on state's coast out to edge of continental shelf. This decision established an important precedent for future cases involving offshore drilling and other uses of coastal waters.

In the dissenting opinion for United States v. Louisiana et al., Justice Black argued that the Submerged Lands Act of 1953 should be interpreted to grant Gulf states rights to offshore lands within their historic boundaries, extending up to three marine leagues (approximately nine nautical miles) from their coastlines. He contended that this interpretation was consistent with Congress's intent when passing the act and historical precedent regarding state boundaries. Furthermore, he disagreed with the majority's reliance on international law principles in interpreting domestic legislation and determining U.S. state borders, arguing instead for a more domestically-focused approach grounded in American legal traditions and history.