Arizona v. Navajo Nation
The Supreme Court ruled that the 1868 treaty establishing the Navajo Reservation did not obligate the federal government to actively secure water for the Navajo Nation, reversing a lower court ruling that had found such a duty.
The decision means the Navajo's request for the government to assess its water obligations and develop a plan to meet the Tribe's needs must be addressed by Congress and the President — not the courts.
How it got here: The district court dismissed the Navajo's complaint; the Ninth Circuit reversed; Arizona and the federal government separately petitioned the Supreme Court, which agreed to hear both cases together.
The Case in Depth
What happened
The Navajo Nation, the largest Native American tribe by land area, occupies a 17-million-acre reservation in the arid West where water is scarce. In some parts of the reservation, up to 91% of households lack reliable water access. The Tribe sued the federal government, arguing that the 1868 peace treaty that established the reservation required the government to assess the Tribe's water needs and develop a plan to meet them — potentially including building pipelines, wells, or other water infrastructure. Three western states intervened to protect their own Colorado River water interests.
The question before the Court
Did the 1868 peace treaty between the United States and the Navajo Nation require the federal government to take active steps to find and secure water for the Tribe?
The Court's answer
No — the 1868 treaty, while it reserved water rights for the Navajo Reservation (enough water to make the reservation livable, consistent with the long-standing Winters doctrine), did not require the federal government to take affirmative steps to find and secure water for the Tribe. The treaty imposed specific duties on the United States — building schools, supplying seeds and tools — but said nothing about any obligation to assess or meet the Tribe's water needs. A court cannot rewrite or expand a treaty beyond its clear terms.
The Court also declined to fill that gap by invoking the general trust relationship between the United States and Indian tribes. Because the federal government is a sovereign — not a private trustee — courts can enforce only the specific duties that a treaty, statute, or regulation expressly creates. No such provision imposed a water-securing duty here. Addressing the Navajo's modern water needs is a task for Congress and the President, not the judiciary.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
The Navajo Nation — whose members often use just 7 gallons of water per day, one-tenth the national average — cannot use this lawsuit to force the federal government to assess or act on the Tribe's water rights. Securing better access to Colorado River water will require congressional action. Other tribes in similar situations face the same barrier when trying to enforce water-related treaty obligations through the courts.
What changes now
The Navajo's current lawsuit is dismissed and the Ninth Circuit's ruling is reversed. The Tribe retains its reserved water rights under the 1868 treaty — the Winters doctrine remains intact — and the Court noted the Navajo may still seek to intervene in Colorado River water-rights litigation to assert those rights directly. But compelling the federal government to assess or plan for the Tribe's water needs will require an act of Congress, not a court order.
What this does not decide
The ruling does not decide how much water the Navajo's treaty rights include, whether the federal government has already interfered with existing Navajo water rights in a way courts could remedy, or whether the Tribe could succeed in intervening in pending Colorado River water litigation. The Court explicitly left those questions open.
Concurrences and dissents
Concurrence — Justice Thomas
Justice Thomas joined the majority in full but wrote separately to flag a broader problem: decades of Supreme Court opinions loosely invoking a 'trust relationship' between the United States and Indian tribes have blurred the line between the government's moral obligations and legally enforceable fiduciary duties. He argued this amorphous language lacks any clear basis in the Constitution's text or in history, has been used inconsistently to both expand and restrict tribal rights, and should be clarified in future cases.
Dissent — Justice Gorsuch
Justice Gorsuch argued the majority misread the Tribe's lawsuit: the Navajo never asked for pipelines or infrastructure — they asked only for an accounting of the water rights the government already admits it holds in trust for them. He argued the majority also used the wrong legal framework, importing a money-damages test from Tucker Act cases into a request for simple equitable relief under the treaty. In his view, the government's acknowledged role as a fiduciary with pervasive control over the adjacent Colorado River was more than enough to require it to account for what it holds on the Tribe's behalf.
How the Court got there
The legal reasoning, step by step
- The Court started from the rule that governs breach-of-trust claims against the federal government: to make such a claim stick, a tribe must point to specific 'rights-creating or duty-imposing' language in a treaty, statute, or regulation. Broad statements that the United States maintains a 'general trust relationship' with tribes are not enough on their own to create enforceable legal duties.
- Examining the 1868 treaty's text, the Court found it imposed several concrete duties on the government — building schools and a chapel, providing teachers, supplying seeds and farming tools — but contained no language whatsoever requiring the United States to assess or actively secure water for the Tribe. Courts cannot rewrite or expand a treaty beyond those clear terms.
- The Court rejected the Tribe's argument that the treaty's promise of a 'permanent home' implied a duty to secure water. The permanent-home language established where the Tribe could live; it did not, the Court held, add new affirmative obligations the treaty text never stated.
- The Tribe also argued that because the United States once opposed the Navajo's attempt to intervene in Colorado River litigation, that showed governmental control over water — and control, the Tribe said, creates trust duties. The Court rejected this: federal liability for breach of trust 'cannot be premised on control alone'; a specific legal duty must be expressly accepted in text.
- The Court drew on separation-of-powers reasoning to explain why judges should not fill the gap. Water allocation in the arid West is a zero-sum problem with real consequences for multiple states and users. Updating a 155-year-old treaty to address modern water needs is the kind of policy judgment the Constitution assigns to Congress and the President, not the courts — and in fact Congress has repeatedly legislated to assist the Navajo and others with western water infrastructure.
Doctrinal impact
Cases affected by this decision
Reaffirms Winters v. United States (207 U.S. 564)
The Court confirmed that reservations implicitly carry reserved water rights sufficient to fulfill their purpose, but clarified that doctrine creates no affirmative government duty to secure that water.
Reaffirms United States v. Jicarilla Apache Nation (564 U.S. 162)
The Court reaffirmed that enforceable trust duties require specific treaty, statute, or regulatory text — general trust-relationship language is not enough.