In the 1989 case of Georgia v. South Carolina, the U.S. Supreme Court was asked to resolve a dispute over the boundary line between these two states along their shared river border. The controversy arose due to changes in the Savannah River's course over time and disagreements about how previous treaties defined this boundary. The court appointed a Special Master who recommended that most of Georgia's claims be rejected, but also proposed some adjustments favoring both states based on principles of accretion (gradual land increase) and avulsion (sudden land change). Both states filed exceptions to this report. The Supreme Court largely adopted the Special Master’s recommendations with minor modifications, ruling that an island which had formed from sediment deposits belonged to South Carolina as it fell on their side of the original boundary line despite being closer geographically to Georgia at present day due to shifts in river flow patterns. However, they agreed with Georgia that certain other areas should be recognized as part of its territory because they were created by slow accretion rather than sudden avulsion events.

In the dissenting opinion for Georgia v. South Carolina, 1989, Justice Scalia disagreed with the majority's decision to alter a long-standing boundary between two states based on new evidence of an old river channel. He argued that such changes should only be made if there was clear and convincing proof that a mistake had been made in establishing the original boundary line - something he felt was not present in this case. Furthermore, he expressed concern about the potential implications of this ruling for other interstate boundaries across America which could also be subject to change due to shifting natural features like rivers or coastlines. In his view, stability and certainty were more important than absolute accuracy when it came to state borders.