United States v. Claflin is a United States Supreme Court case that was decided in 1878. The case involved a dispute between the United States and the Claflin family over the ownership of a parcel of land in the state of California. The Claflin family had purchased the land from the Mexican government in 1845, and the United States had subsequently acquired the land from Mexico in 1848. The Claflin family argued that they were the rightful owners of the land, while the United States argued that the land had been acquired through the Treaty of Guadalupe Hidalgo and was therefore the property of the United States. The Supreme Court ultimately sided with the United States, ruling that the land had been acquired through the Treaty of Guadalupe Hidalgo and was therefore the property of the United States. The Court held that the Claflin family had no legal right to the land, as they had purchased it from a foreign government that no longer had any claim to it. The Court also held that the United States had acquired the land through a valid treaty and had the right to possess it. This decision established the principle that the United States has the right to acquire land through valid treaties and that private individuals cannot claim ownership of such land.

In United States v. Claflin, the Supreme Court was asked to decide whether a federal district court had jurisdiction over an action brought by the United States against two individuals for alleged violations of the Revenue Act of 1864. The majority opinion held that because Congress had not provided any specific grant of authority to bring such actions in federal courts, there was no basis for finding jurisdiction and thus dismissed the case. Justice Field dissented from this ruling on several grounds. He argued that since Congress had given broad powers to district courts under Article III of the Constitution, it should be presumed that they were authorized to hear cases involving revenue laws unless specifically excluded by statute or other law; he also noted that allowing suits like these would help ensure uniformity in their enforcement throughout all states and territories as well as promote public confidence in them. Finally, he pointed out how similar cases have been heard before without objection from either party involved or anyone else - suggesting a tacit acceptance among all parties concerned about its validity and necessity at least until now when challenged directly here today.