On June 1, 2021, the Supreme Court decided United States v. Cooley, No. 19-1414, holding that Indian tribe police officers retain authority to search and temporarily detain suspected non-Indian criminals on public rights-of-way within the tribe’s reservation.

In Cooley, the Court considered the propriety of a stop of a non-Indian motorist effectuated by an Indian nation’s police officer on a public right-of-way running through the officer’s reservation. During the stop, the officer searched and detained the driver (Cooley) because he suspected that Cooley — who presented with watery, bloodshot eyes, had two semiautomatic rifles beside him on the front seat of his vehicle, and was in visible possession of a glass pipe and bag of methamphetamine — was violating state and federal law. The officer then transferred the driver to the proper non-tribal authorities.

After a federal grand jury indicted Cooley on drug and firearms charges, the district court granted his motion to suppress evidence that the tribal police officer had seized, concluding that the seizure exceeded the officer’s authority. On appeal, the Ninth Circuit affirmed and denied the Government’s motion for rehearing en banc.

The Supreme Court vacated the Ninth Circuit’s decision. The Court began by repeating its longstanding rule that Indian nations’ generally lack jurisdiction over non-Indians, subject to the two “Montana exceptions” established in Montana v. United States, 450 U.S. 544, 565 (1981). Most relevant here, the Court concluded, was the tribe’s inherent power to regulate conduct of non-Indians within its reservation, where that conduct “directly threatens or has some direct effect on the political integrity, the economic security, or the health and welfare of the tribe.” The Court concluded that this exception “fits almost like a glove here.” Finding no evidence that Congress had sought to exercise its power to limit Indian nations’ sovereignty in this regard, the Court held that the tribal police officer possessed the authority to search and temporarily detain Cooley, a non-Indian using a public right-of-way in the reservation, for suspected criminal conduct.

Justice Breyer delivered the opinion for a unanimous Court. Justice Alito filed a concurring opinion.

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