The United States Supreme Court case of The United States v. William Mills' Heirs involved a dispute over the ownership of land in the state of Georgia. At issue was whether or not certain lands were part of a grant made by Congress to the Creek Nation, and thus belonged to them, or if they had been sold off as private property prior to that grant being issued. The court ultimately ruled in favor of the heirs, finding that there was sufficient evidence showing that these lands had indeed been sold off before Congress granted them to the Creek Nation and therefore belonged solely to William Mills’ heirs. This decision established an important precedent for future cases involving Native American land rights disputes with regard to congressional grants.

In the case of The United States v. William Mills' Heirs, the Supreme Court was asked to decide whether a patent issued by Congress in 1820 for land in Arkansas could be revoked due to non-payment of taxes. The majority opinion held that since the patent had been granted before Arkansas became a state and was not subject to taxation at that time, it could not be revoked on those grounds. However, Justice McLean dissented from this decision arguing that while patents were generally exempt from taxation prior to statehood, they should still be subject after statehood if there is an express provision allowing such revocation or forfeiture found within the laws of the new state. Furthermore he argued that even though no such provisions existed in Arkansas’s law at this time, it did not necessarily mean they would never exist as states are allowed some flexibility when creating their own laws regarding property rights and tax collection.