The United States v. Louisiana et al., also known as the Louisiana Boundary Case, was a Supreme Court case in 1981 that dealt with territorial boundaries and jurisdiction over offshore resources. The dispute arose when the federal government claimed ownership of submerged lands and their natural resources off the coast of Louisiana up to three geographical miles from its coastline under the Submerged Lands Act (SLA) of 1953. However, Louisiana argued for control extending further into the Gulf of Mexico based on historical claims dating back to its time as a French colony. The court ruled in favor of the U.S., asserting that it had paramount rights over these areas due to international law principles regarding national sovereignty and security interests, which superseded any state-level claims or colonial-era grants by foreign powers.

In the dissenting opinion for United States v. Louisiana et al., Justice William Rehnquist disagreed with the majority's interpretation of the Submerged Lands Act (SLA) and its application to this case. He argued that Congress intended for states to have rights over submerged lands up to three geographical miles from their coastlines, regardless of whether those lines were drawn from inland waters or seaward-facing coasts. The majority's decision, he contended, effectively redefined "coastline" in a way not intended by Congress when it passed the SLA. Furthermore, he criticized what he saw as an overly complicated method used by the Court to determine coastline boundaries and suggested that a simpler approach would be more consistent with congressional intent.