Texas v. Louisiana

Background

The dispute involved the States of Texas and Louisiana, the United States, and local interests such as the city of Port Arthur over the border through Sabine Pass, Sabine Lake, Sabine River, and out into the Gulf of Mexico. Earlier rulings had fixed the inland boundary at the geographic middle of the Sabine waterways and left some island ownership issues for later proceedings. The United States at one point claimed several western islands but later limited its claim to a single island called "Sam." A Special Master held hearings and issued a detailed report with proposed boundary lines and other recommendations.

Reasoning

The Court considered whether the Special Master correctly located the river channels, assigned island ownership, and drew the offshore boundary. Louisiana objected to which river channel the Master used; Texas objected to measuring the offshore line without reference to the coastline that existed when Texas joined the Union. The Court found the Special Master’s approach consistent with earlier holdings, accepted his factual analysis about the channels, denied the United States’ claim to the island "Sam," and applied the equidistant (median) principle from the 1958 Convention. Reading Articles 8 and 12 together, the Court concluded the median line should be measured with reference to the jetties at the mouth of the Sabine River.

Real world impact

The ruling fixes the state line through the waterways and into the Gulf using an equidistant median measured to the jetties, resolves the disputed island claim, and requires the parties to submit a proposed decree within 90 days. It affects who controls nearby seabed rights and clarifies how man-made harbor works figure into coastal boundary drawing.