Arizona v. Navajo Nation

The Navajo Nation relied on the 1868 Treaty and general federal trust principles to argue that the government must affirmatively identify and secure the tribe's water rights in ongoing adjudications. Under the rule applied here, such affirmative duties require explicit statutory or treaty language; general trust language alone cannot impose obligations to procure specific resources. Examining the treaty's text, the Court found no express mandate requiring the government to take affirmative steps to obtain water for the tribe, distinguishing between the government's passive trust duty not to interfere with tribal interests and an active duty to affirmatively procure water rights on the tribe's behalf. Consequently, despite the federal trust relationship, the government had no legal obligation to assert the Navajo Nation's water claims in the Colorado River adjudications.