Sharp v. Murphy, 591 U.S. 977 (2020), was a Supreme Court of the United States case of whether Congress disestablished the Muscogee (Creek) Nation reservation. After holding the case from the 2018 term, the case was decided on July 9, 2020, in a per curiam decision following McGirt v. Oklahoma that, for the purposes of the Major Crimes Act, the reservations were never disestablished and remain Indian country.

In 1866, Congress established reservation boundaries for the Muscogee (Creek), Cherokee, Chickasaw, Choctaw, and Seminole Nations. The Muscogee (Creek) Nation boundaries composes three million acres in Eastern Oklahoma, including most of the city of Tulsa. The boundaries for all five nations consist of over 19 million acres and nearly the entire eastern half of Oklahoma. In 1907, Congress admitted Oklahoma to the Union as the 46th state and federal territorial courts immediately transferred all non-federal cases involving Native Americans to state courts. However, in the process, it has been found that Congress never officially disestablished the tribal reservations, a requirement for a tribal reservation to lose that status as demanded under Solem v. Bartlett (1984).

The situation arose following the appeal of a convicted murderer, Patrick Murphy, a member of the Muscogee-Creek tribe, with his crime taking place within the boundaries of Muscogee-Creek reservation as delimited by Congress in 1866. The appeal addressed whether the federal territorial courts had congressional authorization to make this transfer, as if the lands were still a tribal reservation, Murphy's crime would become subject to federal jurisdiction rather than Oklahoma. Although this case is specific to the Muscogee (Creek) Nation, the Court's decision is likely to also apply to reservations of the Cherokee, Choctaw, Chickasaw, and Seminole Nations because all five tribes have similar histories within the state of Oklahoma.

The case was first heard by the Supreme Court in its 2018–2019 term; Justice Neil Gorsuch recused himself due to having participated as a federal appellate judge when the case was heard in lower courts, which created a potential deadlock between the remaining eight Justices. The Supreme Court announced at the end of the term that it would hold additional oral arguments during the 2019 term. It also heard a second case, McGirt v. Oklahoma, in May 2020 involving similar matters and which Justice Gorsuch had no prior conflict with.

From the colonial and early federal period in the history of the United States the Cherokee, Chickasaw, Choctaw, Muscogee (Creek), and Seminole Nations became known as the Five Civilized Tribes. These are the first five tribes that Anglo-European settlers generally considered to be "civilized". The "Five Tribes" once occupied much of the land in current day Alabama, Florida, Georgia, Mississippi, South Carolina and Tennessee.

In the 1830s, Congress forcibly removed these tribes from their ancestral homelands to designated Indian Territory. The migration from these homelands to the designated territory is infamously known as the Trail of Tears. During the American Civil War, some of the tribes supported the Confederates. After the Union victory, the "Five Tribes" ceded all its territory in western Oklahoma. The Muscogee (Creek)'s present boundaries reflect two cessions. In 1856, the Muscogee (Creek) Nation "cede[d]" lands to the Seminoles. In 1866, Congress signed the Treaty with the Creek where the Muscogee (Creek) Nation "cede[d] ... to the United States" lands in return for $975,168.

In the 1880s, the "Allotment Era" swept the Western United States. The Dawes Act of 1887 (also known as the General Allotment Act or the Dawes Severalty Act of 1887) authorized the President of the United States to survey Native American tribal land and divide it into allotments for individual Native Americans. Those who accepted allotments and lived separately from the tribe would be granted United States citizenship. The Curtis Act of 1898 amended the Dawes Act to extend its provisions to the Five Civilized Tribes; it required abolition of their governments, allotment of communal lands to people registered as tribal members, and sale of lands declared surplus, as well as dissolving tribal courts.

The Muscogee (Creek) Nation reached a negotiated agreement with the federal government for the allotment of tribal lands, and Congress passed it into law in 1901. The original agreement specified that its terms would control over conflicting federal statutes and treaty provisions, but it in no way affected treaty provisions consistent with the agreement. The agreement's central purpose was to facilitate a transfer of title from the Muscogee (Creek) Nation generally to its members individually. It provided that "[a]ll lands belonging to the Creek tribe", except for town sites and lands reserved for public purposes, should be appraised and allotted "among the citizens of the tribe". In 1906, Congress passed the Oklahoma Enabling Act, which empowered the people residing in Indian Territory and Oklahoma Territory to elect delegates to a state constitutional convention and subsequently to be admitted to the union as a single union. The question before the Supreme Court is whether these laws and other similar federal statutes clearly disestablished the reservation of the Muscogee (Creek) Nation.