The case of Reagan v. United States in 1900 revolved around a dispute over land ownership rights between the U.S. government and private citizens, specifically involving lands within Indian reservations that were opened for settlement under the General Allotment Act of 1887 (also known as the Dawes Act). The plaintiffs, including John R. Reagan, claimed they had validly purchased plots from individual Native Americans who had received allotments under this act. However, these transactions violated an amendment to the Dawes Act which prohibited such sales for a period of twenty-five years without presidential approval. The Supreme Court ruled against Reagan and his co-plaintiffs on two main grounds: firstly, it held that their purchases were illegal due to lack of required presidential consent; secondly, it found that even if such consent was not necessary or could be retroactively granted by Congress (as argued by some), no such grant existed in this case. This decision reinforced federal authority over public lands and affirmed protections for Native American property rights against unauthorized transfers.

In the dissenting opinion for Reagan v. United States, Justice John Marshall Harlan argued that the jury should have been allowed to consider whether or not defendant's false statements were material to his conviction of perjury. He believed that it was a question of fact and thus within their purview, rather than a matter of law for the judge alone to decide. Harlan contended that this principle was well-established in English common law and had been adopted by American courts as well. He also pointed out inconsistencies in previous rulings on similar cases where sometimes juries were permitted to determine materiality while other times they weren't. In conclusion, he asserted that denying jurors this right undermined their role as triers of fact and potentially led to unjust outcomes.