In the case of State of Arizona v. State of California et al., 2005, the Supreme Court was asked to resolve a dispute over water rights between several western states and Native American tribes. The issue at hand was how much water from the Colorado River each state and tribe were entitled to under various federal laws and agreements. The court had previously decided on this matter in 1963 but due to changes in circumstances, including population growth and new legal issues involving tribal rights, it agreed to reconsider its original decision. However, after hearing arguments from all parties involved, the court ultimately upheld its previous ruling with minor modifications regarding surplus conditions. It reaffirmed that Arizona is entitled to 2.8 million acre-feet annually while California's allotment remained capped at 4.4 million acre-feet per year unless surplus conditions exist.

In the dissenting opinion for the case of STATE OF ARIZONA v. STATE OF CALIFORNIA et al., Justice Stevens argued that Arizona's claim was not barred by res judicata, a legal principle preventing an issue from being re-litigated once it has been resolved. He believed that there were significant differences between this case and its predecessor, which justified reconsideration of the issues at hand. Furthermore, he disagreed with the majority's interpretation of Section 5(a) of the Boulder Canyon Project Act (BCPA), arguing instead that it should be read to allow Arizona to bring suit against California over water rights disputes arising after 1964 when Congress approved Arizona’s Colorado River allocation plan. The justice also contended that even if Section 5(a) did bar such suits, it would violate Article III of Constitution as interpreted in South Carolina v Regan because it effectively deprives states like Arizona their right to seek redress before Supreme Court for injuries caused by other states.