In the case of Colorado v. New Mexico et al., 1982, the Supreme Court ruled in favor of New Mexico, upholding that state's right to use water from the Vermejo River, a tributary of the Canadian River. The dispute arose when Colorado sought to divert water from this river for its own use. However, under an interstate compact signed by both states and ratified by Congress in 1950 - known as the Canadian River Compact - it was agreed that each state had specific rights to certain amounts of water from this river system based on "equitable apportionment." In its decision, which was delivered by Justice Byron White with Justices William Rehnquist and Sandra Day O'Connor dissenting, the court held that Colorado failed to prove by clear and convincing evidence that its proposed diversion would not deplete New Mexico’s share or cause substantial injury to New Mexico’s interests.

In the dissenting opinion for Colorado v. New Mexico et al., 1982, Justice O'Connor disagreed with the majority's decision to apply a strict "clear and convincing" evidence standard in resolving interstate water disputes. She argued that this high evidentiary threshold was not required by either precedent or principles of equity, and it could unduly hinder states' abilities to secure their equitable shares of interstate waters. Instead, she suggested that a preponderance of the evidence standard would be more appropriate as it is generally used in most civil cases involving property rights disputes. Furthermore, she expressed concern about how the majority's ruling might affect future negotiations between states over shared water resources because it may discourage settlements if one state believes they can meet this higher burden of proof at trial.