Davidson v. Lanier was a United States Supreme Court case that was decided in 1866. The case involved a dispute between two parties over a contract for the sale of a slave. The plaintiff, Davidson, had entered into a contract with the defendant, Lanier, to purchase a slave for $1,000. Davidson paid the full amount, but Lanier refused to deliver the slave. Davidson then sued Lanier for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court noted that the contract was not illegal under the laws of the state in which it was made, and that the parties had the right to enter into such a contract. The Court also held that the contract was binding on both parties, and that Lanier was liable for damages for breach of contract. The Court awarded Davidson the full amount of the purchase price, plus interest. The decision in Davidson v. Lanier established that contracts for the sale of slaves were valid and enforceable under the law. This decision was significant in that it provided legal protection for parties who entered into such contracts. It also established that the parties to such contracts were legally bound to fulfill their obligations.

In Davidson v. Lanier, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a citizen of one state against another in which the cause of action arose from property located in yet another state. The majority opinion held that such jurisdiction did not exist and that the case should be dismissed for lack of subject matter jurisdiction. However, Justice Field dissented on this issue, arguing that it would be unjust to deny citizens access to justice simply because their claims arise out of different states than those where they reside or are sued. He further argued that if Congress had intended for there to be no federal question involved when two citizens from different states have disputes involving property located in a third state then it would have made its intentions clear through legislation rather than leaving it up to judicial interpretation. In conclusion, Justice Field believed that denying access to justice based solely on jurisdictional grounds was contrary both to public policy and natural justice and thus he disagreed with the majority's decision dismissing the case without prejudice due lack of subject matter jurisdiction