South Dakota v. Yankton Sioux Tribe

In 1858, the Yankton Sioux Tribe (the tribe) (plaintiff) entered a treaty with the United States. Pursuant to the treaty, the tribe ceded more than 11 million acres of its territory to the United States, and a formal reservation was established within the remaining territory of approximately 430,000 acres. Later, the Dawes Act provided for the allotment of 160-acre tracts within the reservation to individual tribal members. This process left a surplus of approximately 168,000 unallotted acres. In 1892, the United States negotiated a new agreement with the tribe for the sale, cession, and relinquishment of the unallotted lands in return for a fixed payment of $600,000. However, the agreement also included a savings clause stating that all provisions of the 1858 treaty were to remain in effect. The 1892 agreement was ratified by an act of Congress in 1894. Within the next few years, the newly ceded lands were rapidly settled by Whites. Also, many members of the tribe sold their allotments to non-Indians. The tribal population of the area gradually declined as Whites became a majority. Much later, a group of counties in South Dakota (the state) (defendant) formed a waste-management district and acquired a landfill site located on land that formerly fell within the formal reservation. The site’s previous owner had been a non-Indian. The tribe brought suit in federal district court, seeking an injunction against the landfill’s construction. The court found in favor of the tribe, holding that the 1894 act left the reservation undiminished. The federal court of appeals affirmed. The state appealed to the United States Supreme Court.