## Facts

- A tribal police officer on patrol on the Crow Reservation in Montana approached a pickup truck parked on the shoulder of a U.S. highway right-of-way within the reservation to check on the driver.
- The driver, Joshua James Cooley, appeared non-Indian, had watery and bloodshot eyes, and provided an unusual explanation for his presence.
- The officer observed two semiautomatic rifles on the front seat and saw a pistol when he opened the passenger door.
- Fearing for safety, the officer ordered Cooley out, conducted a pat-down, and found small plastic bags commonly used for packaging methamphetamine.
- Looking into the vehicle, the officer saw a glass pipe and a bag containing methamphetamine; additional officers arrived and contraband was seized.
- Cooley was federally indicted on drug and firearm charges.
- The district court suppressed the evidence, and the Ninth Circuit affirmed, reasoning that tribal officers lacked authority to investigate non-Indians for state or federal violations on public rights-of-way absent an “apparent” violation and after determining Indian status.

## Issues

1. Whether a tribal police officer may temporarily detain and search a non-Indian on a public right-of-way within a reservation based on suspected violations of state or federal law.
2. Whether tribal officers must first determine Indian/non-Indian status and may detain non-Indians only for “apparent” violations of law.

## Decision

- The Supreme Court unanimously vacated the Ninth Circuit’s judgment and remanded.
- The Court held that a tribal police officer has authority to briefly detain a non-Indian on a public right-of-way within a reservation for potential violations of state or federal law.
- The Court further held that the authority to search a detained non-Indian, as appropriate for officer safety and transport to other authorities, is ancillary to that detention authority.
- The Court rejected the Ninth Circuit’s status-first requirement and its “apparent violation” limitation as unworkable.
- The case was remanded for further proceedings, including evaluation of whether the detention and search satisfied applicable Fourth Amendment standards (e.g., reasonable suspicion or probable cause).

## Legal Principles

- Tribes retain inherent authority over nonmember conduct on reservations when that conduct threatens or directly affects the health or welfare of the tribe.
- Under that retained authority, tribal police may conduct brief investigatory detentions of non-Indians on reservation roadways to address potential violations that endanger public safety (including drug trafficking and impaired driving).
- Even when ultimate criminal prosecution lies with federal or state authorities, tribal officers may detain non-Indians and deliver them to proper authorities; a limited search incident to detention/transport may be permissible as an ancillary measure.
- Courts should not impose special roadside rules requiring prior determination of Indian status or restricting detention to an undefined “apparent violation” threshold.

## Conclusion

The Court held that tribal police may briefly detain and, where appropriate, search non-Indians on public rights-of-way within reservations to address suspected state or federal law violations threatening reservation safety, and it returned the case for assessment of the stop and search under ordinary Fourth Amendment-type standards.


United States v. Cooley, 141 S. Ct. 1638 (2021)