Mississippi v. Louisiana

Background

This case was brought by the two states involved in a dispute over where the official boundary line between Mississippi and Louisiana runs in several river and island areas. The State of Louisiana filed formal objections (called exceptions) to a Special Master’s written report that mapped the boundary using river channels and precise geographic coordinates. The matter was submitted to the Court after written pleadings, evidence, exhibits, and arguments by lawyers for the parties.

Reasoning

The key question was simply what the true state boundary is at the places involved. The Court reviewed the Special Master’s report and Louisiana’s exceptions, overruled those exceptions, and approved the Special Master’s proposed decree. The Court’s order describes the boundary in detail by referring to the live thalweg (the main river channel), dead thalwegs of abandoned channels, and specific latitude/longitude points that run through Reed-Bedford, Oak Bend, Diamond Island, Diamond Point, Palmyra Lake, and Kellogg Lake. By adopting the report, the Court settled the dispute over where the border lies in those areas.

Real world impact

The decree establishes an official, court-ordered line between Mississippi and Louisiana at the listed river and island locations, using mapped coordinates and river features. The order is a final judicial finding of those boundaries in this cause, and it also directs that the legal costs of the suit be divided equally between the two states.