Embry v. United States is a United States Supreme Court case that was decided in 1879. The case involved a dispute between the United States and a private citizen, John Embry, over the ownership of a parcel of land in the state of Kentucky. Embry claimed that he had purchased the land from the United States in 1845, but the United States argued that the land had been sold to another party in 1847. The Supreme Court held that the United States had not sold the land to Embry in 1845, and that the sale to the other party in 1847 was valid. The Court reasoned that the United States had the right to sell the land to whomever it chose, and that Embry had no legal claim to the land. The Court also held that the United States was not liable for any damages that Embry may have suffered as a result of the sale. In conclusion, the Supreme Court held that the United States had not sold the land to Embry in 1845, and that the sale to the other party in 1847 was valid. The Court also held that the United States was not liable for any damages that Embry may have suffered as a result of the sale.

Justice Field delivered the dissenting opinion in Embry v. United States, arguing that the majority's decision was contrary to both precedent and sound legal reasoning. He argued that a contract between two parties should be enforced according to its terms, regardless of any subsequent changes in law or public policy. In this case, he noted that the government had entered into a contract with Embry for his services as an Indian agent without specifying any particular term of service; thus, it could not later claim damages from him on account of his having served beyond what Congress subsequently deemed reasonable. Furthermore, Justice Field pointed out that if contracts were subject to such retroactive modification by legislative action then no one would ever feel secure entering into agreements with the government since their rights under those agreements could always be altered at some future date by new legislation. Therefore, he concluded that while Congress may have had good intentions when enacting laws limiting Indian agents' terms of service they did not have authority to impose them retrospectively upon existing contracts like Embry's and thus must bear whatever losses resulted from their own failure to include such provisions when originally contracting with him.