A unanimous Court holds that tribal police officers have the power to search and temporarily detain non-Indians suspected of breaking federal or state laws within reservations.
Cooley was in a truck stopped on the side of a state highway traversing the Crow Reservation in Montana. Believing any occupants might need assistance, a tribal police officer approached the truck and spoke to Cooley, who appeared to be non-native, had some indicia of intoxication, and had two rifles on the front seat. The officer ordered Cooley out of the truck and patted him down, and eventually discovered methamphetamine. Cooley was arrested, questioned by state and federal officers, and charged with federal drug and weapons offenses. (Slip op. 1-2).
Cooley challenged the seizure and search of him on the grounds the office lacks the authority to investigate nonapparent violations of state or federal law by a non-Indian on a public road crossing a reservation. The Court has previously said that a tribe retains inherent sovereign authority to address “conduct [that] threatens or has some direct effect on … the health or welfare of the tribe.” Montana v. United States, 450 U.S. 544, 566 (1981), and it holds that this statement of law governs here and the tribal officer was therefore authorized to detain and search Cooley.
While Indian tribes are “distinct, independent political communities” exercising sovereign authority, Worcester v. Georgia, 6 Pet. 515, 559 (1832), the sovereignty they retain is of “a unique and limited character,” United States v. Wheeler, 435 U.S. 313, 323 (1978). In particular, tribes lack inherent sovereign power to exercise criminal jurisdiction over non-Indians, Oliphant v. Suquamish Tribe, 435 U.S. 191, 212 (1978), and tribal authority always remains subject to the plenary authority of Congress, Michigan v. Bay Mills Indian Community, 572 U.S. 782, 788 (2014).
There is no treaty or statute divesting Indian tribes of the authority to detain and search non-Indians traveling through Indian land, so the Court turns to precedent to determine whether a tribe has retained inherent sovereign authority to exercise that power. It finds Montana v. United States to be “highly relevant”:
In that case we asked whether a tribe could regulate hunting and fishing by non-Indians on land that non-Indians owned in fee simple on a reservation. We held that it could not. We supported our conclusion by referring to our holding in Oliphant that a tribe could not “exercise criminal jurisdiction over non-Indians.” Montana, 450 U.S. at 565. We then wrote that the “principles on which [Oliphant] relied support the general proposition that the inherent sovereign powers of an Indian tribe do not extend to the activities of nonmembers of the tribe.” Ibid.
At the same time, we made clear that Montana’s “general proposition” was not an absolute rule. Ibid. We set forth two important exceptions. First, we said that a “tribe may regulate, through taxation, licensing, or other means, the activities of nonmembers who enter consensual relationships with the tribe or its members, through commercial dealing, contracts, leases, or other arrangements.” Ibid. Second, we said that a “tribe may also retain inherent power to exercise civil authority over the conduct of non-Indians on fee lands within its reservation when that conduct threatens or has some direct effect on the political integrity, the economic security, or the health or welfare of the tribe.” Id., at 566 (emphasis added).
The second exception we have just quoted fits the present case, almost like a glove. The phrase speaks of the protection of the “health or welfare of the tribe.” To deny a tribal officer authority to search and detain for a reasonable time any person he or she believes may commit or has committed a crime would make it difficult for tribes to protect themselves against ongoing threats. Such threats may be posed by, for instance, non-Indian drunk drivers, transporters of contraband, or other criminal offenders operating on roads within the boundaries of a tribal reservation. ….
We have subsequently repeated Montana’s proposition and exceptions in several cases involving a tribe’s jurisdiction over the activities of non-Indians within the reservation. …. In doing so we have reserved a tribe’s inherent sovereign authority to engage in policing of the kind before us. …. (Slip op. 4-5).
The Court also says that its prior cases denying tribal jurisdiction over the activities of non-Indians on a reservation rested in part upon the fact that full tribal jurisdiction would require the application of tribal laws to non-Indians who do not belong to the tribe and consequently had no say in creating the laws that would be applied to them. “[The] search and detention [in this case], however, do not subsequently subject Cooley to tribal law, but rather only to state and federal laws that apply whether an individual is outside a reservation or on a state or federal highway within it.” (Slip op. 7).