## Facts

- An 1868 treaty established the Navajo Reservation as the Tribe’s “permanent home,” largely within the Colorado River Basin.
- Under the reserved-rights doctrine, creation of a reservation implicitly reserves the amount of water necessary to fulfill the reservation’s purposes.
- In 2003, the Navajo Nation sued federal agencies, alleging breach of trust for failing to secure adequate water for the Reservation.
- The Nation did not allege federal interference with existing Navajo water uses; it sought to compel affirmative federal action, including assessing needs, developing a plan to secure water, and potentially building water infrastructure.
- Arizona, Nevada, and Colorado intervened to protect their interests in Colorado River water.
- The district court dismissed the breach-of-trust claim; the Ninth Circuit reversed, holding the treaty required the United States to take affirmative steps to secure water.

## Issues

1. Whether the 1868 treaty imposed a judicially enforceable, affirmative trust duty requiring the United States to take specific actions to secure water for the Navajo Nation.

## Decision

- The Supreme Court reversed the Ninth Circuit in a 5–4 decision authored by Justice Kavanaugh.
- The Court held that, although the treaty reserved necessary water to accomplish the Reservation’s purpose, it did not impose an affirmative duty on the United States to take steps to secure water for the Tribe.
- Because the Nation identified no treaty, statute, or regulation creating the specific duties it sought to enforce, the breach-of-trust claim seeking compelled planning and development was not cognizable.
- Justice Thomas concurred.
- Justice Gorsuch dissented, joined by Justices Sotomayor, Kagan, and Jackson.

## Legal Principles

- Tribes asserting breach-of-trust claims against the United States must identify a substantive source of law (treaty, statute, or regulation) that creates specific, judicially enforceable duties.
- The federal government owes enforceable fiduciary duties to a tribe only to the extent it has expressly accepted those responsibilities in governing legal texts.
- An implied reserved water right associated with reservation creation does not, by itself, create an enforceable federal obligation to plan, develop, or deliver water absent textual support.
- Courts may recognize reserved rights but may not impose new affirmative treaty obligations not grounded in the treaty’s text.

## Conclusion

The Court concluded that the 1868 treaty and reserved-rights doctrine may establish Navajo water rights, but they do not authorize courts to compel the federal government to undertake affirmative measures to identify, plan for, or develop water supplies without a specific, text-based duty.


Arizona v. Navajo Nation, 599 U.S. 555 (2023)