The U.S. Supreme Court case Arizona v. California et al., in 1978, was a dispute over water rights of the Colorado River between several states and Native American tribes. The court ruled that five Indian reservations located along the river were entitled to sufficient water from the mainstream to fulfill their agricultural needs, which amounted to approximately one million acre-feet per year. This decision reaffirmed an earlier ruling made by the court in 1963 regarding allocation of Colorado River waters among western states and added further clarification on how much water should be allocated for use by these tribal lands specifically. The ruling also held that federal reserved water rights are not lost through nonuse and can be claimed at any time, thus protecting tribal interests even if they had not previously utilized their full allotment of water.

In the dissenting opinion for Arizona v. California et al., Justice William H. Rehnquist disagreed with the majority's interpretation of a 1963 decree that allocated water from the Colorado River among several states and Mexico. He argued that this decree did not give Secretary of Interior authority to determine how much water each state could use, but rather it was meant to be an apportionment scheme based on percentages agreed upon by all parties involved in the case. Furthermore, he contended that Congress had never intended for one official (the Secretary) to have such power over these allocations without any judicial review or checks and balances system in place. The dissent also expressed concern about potential violations of federalism principles if individual states were denied their rights to manage their own natural resources within legal boundaries set by interstate compacts or Supreme Court decrees.