Montana v. United States

The Crow Tribe's reservation land in Montana was divided into individually owned parcels under the Crow Allotment Act, with lots sold to both Indians and non-Indians; the Crow retained treaty hunting and fishing privileges but later passed a resolution banning all non-Indians from hunting or fishing on the reservation, even on land those non-Indians owned outright. Montana (defendant) continued enforcing its own state hunting and fishing regulations against non-Indian landowners on the reservation, and the United States (plaintiff), suing on the Tribe's behalf, sought a declaration that the Tribe and federal government held exclusive authority over hunting and fishing there; the district court ruled for Montana, the Ninth Circuit reversed in part, finding the Tribe could regulate (though not prohibit) non-Indian fishing and hunting, and the Supreme Court granted certiorari.