The U.S. Supreme Court case Missouri v. Iowa in 1896 was a dispute over the boundary line between the two states, specifically regarding an area of land near the Des Moines River. The controversy arose due to differing interpretations of treaties with Native American tribes and subsequent surveys which resulted in inconsistent maps. In its decision, the Supreme Court upheld a previous ruling from 1849 that had established this boundary based on these early surveys and treaties, despite Missouri's claim that they were flawed or inaccurate. The court ruled against Missouri’s argument for reevaluation of evidence used in determining state lines during earlier proceedings; it held that once boundaries are settled by courts they become conclusive and binding perpetually unless altered by mutual agreement between states involved under Congress’ approval.

In the dissenting opinion for Missouri v. Iowa, 1896, it was argued that the majority's decision to uphold a previous ruling on the boundary dispute between Missouri and Iowa was incorrect. The dissenting justices believed that there were significant errors in both fact-finding and interpretation of law in the original case from 1849. They contended that this earlier judgment had been based on flawed surveys and maps which did not accurately represent historical boundaries or treaties with Native American tribes. Furthermore, they disagreed with how precedent had been applied by their colleagues; they felt prior cases involving territorial disputes should have guided them towards ordering a new survey rather than simply affirming an old one riddled with inaccuracies. Ultimately, these justices held firm to their belief that justice would be better served if more weight were given to accurate geographical data and less reliance placed upon past judicial decisions made under questionable circumstances.