Atkinson Trading Company (Atkinson) (plaintiff), a non-Indian entity, operated a hotel on land owned by Atkinson, but located within the Navajo Reservation. The Navajo Nation imposed a hotel-occupancy tax on all hotel rooms located on the reservation. The tax was charged to hotel guests, but hotel owners were responsible for collecting the tax and remitting those payments to the Navajo Tax Commission (NTC) (defendant). Atkinson disputed the Navajo Nation’s authority to impose the tax. The NTC, Navajo Supreme Court, and lower federal courts upheld the tax. The Tenth Circuit affirmed, holding that the Navajo Nation was authorized to impose the tax under Montana v. United States, 450 U.S. 544 (1981), based on a contractual relationship between Atkinson and the tribe. The United States Supreme Court granted certiorari.