Mississippi v. United States

Background

The dispute involved the State of Mississippi and the United States over claims to an undecided portion of Chandeleur Sound. After the Court granted leave for both to file claims, Mississippi sued and the United States answered. The parties then agreed to a specific straight line to mark the baseline used to measure Mississippi’s grant under the Submerged Lands Act, the federal law that allocates rights to offshore lands and resources.

Reasoning

The Court’s role was limited to entering the parties’ agreed resolution and defining their rights under the Submerged Lands Act. The Court granted the joint motion and issued a decree adopting the stipulated straight line — described by coordinate points running from a point on Ship Island to a point near the Chandeleur Islands — as the permanent baseline for measuring Mississippi’s submerged-lands grant. The decree states that, as against Mississippi, the United States has exclusive rights to explore and exploit the continental shelf reserved to the United States; and, conversely, as against the United States, Mississippi has exclusive rights to explore and exploit the continental shelf on its side, subject to the exceptions in §5 of the Act. The Court enjoined each side and those claiming under them from interfering with the other’s resource rights and retained jurisdiction to enforce the decree.

Real world impact

The decree clarifies which offshore areas are measured as part of Mississippi’s territory and who may develop or lease resources near Chandeleur Sound. It affects government activity, leases, and private exploration in that zone. The order also preserves unresolved issues — including Mississippi’s lateral boundary with Louisiana and the inland-water status of Chandeleur Sound — for future decision.