Tome v. Dubois was a United States Supreme Court case that was decided in 1867. The case involved a dispute between two parties over the ownership of a slave named Mary. The plaintiff, Tome, claimed that he had purchased Mary from the defendant, Dubois, and that Dubois had no right to reclaim her. Dubois argued that he had only loaned Mary to Tome and that she was still his property. The Supreme Court ultimately sided with Tome, ruling that Dubois had no right to reclaim Mary. The Court held that the sale of a slave was a valid contract and that the sale was binding on both parties. The Court also held that the sale of a slave was not subject to the laws of Louisiana, which prohibited the sale of slaves. This ruling established that the sale of a slave was a valid contract and that the sale was binding on both parties.

In the case of Tome v. Dubois, Justice Field delivered a dissenting opinion in which he argued that Congress had no authority to pass legislation allowing for the removal of an individual from one state to another without their consent and against their will. He reasoned that such action would be unconstitutional as it violated both the Fifth Amendment's protection against deprivation of life, liberty or property without due process and also Article IV Section 2 Clause 1 (the Privileges and Immunities Clause) which states "The Citizens of each State shall be entitled to all Privileges and Immunities of Citizens in the several States." Furthermore, Field noted that if Congress was allowed this power then they could use it for any purpose they deemed necessary regardless whether or not it is constitutional. Thus, he concluded by stating his belief that Congress did not have this power under either its enumerated powers nor its implied powers granted by Article I Section 8 Clause 18 (the Necessary & Proper clause).