Arizona v. Navajo Nation

Background

The Navajo Tribe sued the United States, saying the 1868 treaty that created their reservation also required the Government to take affirmative steps to secure needed water, such as assessing needs, planning, and building pipelines or wells. The States of Arizona, Nevada, and Colorado intervened to protect their Colorado River interests. A federal trial court dismissed the suit, the Ninth Circuit allowed it to proceed, and the Supreme Court agreed to decide the dispute.

Reasoning

The Court recognized that the 1868 treaty reserved water for the Navajo Reservation under the Winters doctrine, meaning the Tribe has reserved water rights to make the reservation usable. But the Court found no clear treaty language that imposes a duty on the United States to take affirmative steps to secure water. Because the treaty already included several specific U.S. promises but said nothing about building or securing water, the Court declined to expand the treaty beyond its text and left updates to Congress and the President.

Real world impact

The ruling means the Navajo keep reserved water rights but cannot use this treaty claim to require the federal Government to assess needs, design plans, or construct water infrastructure. The opinion notes tribes may still pursue water claims in water-rights litigation or ask Congress and federal agencies for funding and programs. The decision reversed the Ninth Circuit and leaves policy choices about large water projects to the political branches and to other legal proceedings.

Dissents or concurrances

One Justice wrote separately raising concerns about the general “trust” language. A dissent argued the Tribe only sought an accounting and plan and would have allowed the suit to proceed; that dissent was joined by three other Justices.