In the 1971 case Nebraska v. Iowa, the Supreme Court was tasked with resolving a boundary dispute between the two states. The disagreement arose due to changes in the course of Missouri River, which serves as their shared border. According to an earlier ruling from 1892, it had been established that when a river serving as a boundary shifts gradually over time (a process known as accretion), then state boundaries shift accordingly; however if there is sudden change (avulsion), borders remain fixed at their pre-change location. In this case, both processes occurred simultaneously and created confusion about where exactly the border lay. The court ruled in favor of Iowa by applying principles from previous cases related to avulsion and accretion. It held that despite any gradual changes caused by erosion or deposition along parts of its course, since there was evidence showing that most of Missouri River's movement resulted from avulsive events during flooding periods in late 1940s and early 1950s - these were deemed dominant factors determining final position for disputed sections on interstate boundary line.

The dissenting opinion in the case of Nebraska v. Iowa, 1971, argued that the majority's decision to uphold a previous ruling on the boundary between Nebraska and Iowa was incorrect due to changes in geographical conditions over time. The dissent contended that natural shifts in river channels should be taken into account when determining state boundaries rather than adhering strictly to historical rulings. They believed this approach would better reflect current realities and ensure fair allocation of resources and jurisdictional responsibilities between states. Furthermore, they expressed concern about potential implications for other border disputes if courts rigidly adhere to old decisions without considering evolving circumstances.