Grant v. United States was a Supreme Court case in 1868 that dealt with the issue of whether the United States government had the right to take possession of a vessel that had been seized by the Confederate States during the Civil War. The plaintiff, Grant, was the owner of the vessel, and he argued that the United States had no right to take possession of the vessel without his consent. The Supreme Court ruled in favor of the United States, holding that the United States had the right to take possession of the vessel as a result of the war. The Court reasoned that the United States had the right to take possession of the vessel in order to protect its interests, and that Grant had no right to object to the seizure. The Court also held that the United States had the right to take possession of the vessel in order to prevent it from being used by the Confederate States for military purposes. This ruling established the principle that the United States government has the right to take possession of property during times of war in order to protect its interests.

In Grant v. United States, the Supreme Court was asked to decide whether a contract between two parties could be enforced against the United States government. The majority opinion held that it could not, as contracts with the federal government are subject to Congressional control and must be in accordance with its laws. In his dissent, Justice Field argued that this decision would lead to an unjust result for private citizens who had entered into valid contracts with the government in good faith and relied on them for their livelihoods. He further argued that Congress should not have such broad authority over contractual obligations; rather, he believed these matters should be left up to state courts or other tribunals established by Congress itself if necessary. Ultimately, Justice Field's dissenting opinion did not prevail but it remains an important reminder of how far-reaching congressional power can extend when dealing with private individuals' rights under contract law.