The U.S. Supreme Court case Louisiana v. Mississippi in 1905 was a dispute over the boundary line between the two states, specifically involving an area of land known as South Pass located at the mouth of the Mississippi River. The controversy arose due to changes in river channels and accretions which had altered geographical features since earlier surveys were conducted. Louisiana claimed that it owned all lands lying west of main navigable channel while Mississippi contended that its jurisdiction extended up to certain landmarks identified in previous treaties and agreements regardless of any shifts in river courses or formation of new lands through natural processes. The court ruled against Louisiana's claim, holding that state boundaries established by Congress could not be changed due to alterations caused by natural forces such as erosion or deposition unless explicitly provided for by law or agreement between concerned parties. It affirmed that original boundary descriptions remained valid despite physical changes on ground and thus upheld Mississippi's jurisdiction over disputed territory based on historical demarcations rather than current topographical conditions.

In the dissenting opinion for Louisiana v. Mississippi, Justice Harlan argued that the Supreme Court did not have jurisdiction over this case because it was essentially a political matter rather than a legal one. He believed that disputes between states about their boundaries should be resolved by Congress or through negotiations between the states themselves, not by courts of law. Furthermore, he pointed out that there were no clear legal principles to guide the court's decision in such cases and warned against setting a dangerous precedent where judges would be asked to decide on matters of state sovereignty based on their personal views rather than established laws or constitutional provisions.