The government sued for a declaratory judgment asserting its own reserved rights and those of several Native American tribes, against over 1,000 water users named as defendants.

Even though dismissal of a federal suit to avoid duplicative litigation was something of an exceptional nature, Brennan determined that it was permissible in some circumstances.

He listed factors federal courts may consider in determining the appropriateness of dismissal where concurrent jurisdiction exists: Brennan concluded by explaining that the whole policy advanced by the McCarran Amendment was to avoid "piecemeal adjudication of water rights," which would lead to concurrent litigation with inconsistent outcomes.

Congress was well aware of pre-existing state procedures to determine water rights when it passed the McCarran Amendment.

Brennan held that when all these factors were taken into account, the district court ruled correctly in dismissing the suit.

Justice Stewart agreed with the majority that the McCarran Amendment did not diminish the federal courts' jurisdiction, and that the conventional doctrines of abstention were not implicated here.

In the litigation of water rights, where actual administration or control of a river was not being determined, this rule was clearly unnecessary.