Jacobs v. Baker was a United States Supreme Court case that was decided in 1868. The case involved a dispute between two parties over a contract for the sale of a slave. The plaintiff, Jacobs, had entered into a contract with the defendant, Baker, to purchase a slave for $1,000. Jacobs paid the full amount, but Baker refused to deliver the slave. Jacobs then sued Baker 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 Jacobs was entitled to recover the full amount of the purchase price. In its decision, the Court also noted that the contract was not contrary to public policy, as slavery had been abolished in the United States. The Court held that the contract was valid and enforceable, and that Jacobs was entitled to recover the full amount of the purchase price.

In Jacobs v. Baker, the Supreme Court was tasked with determining whether a contract between two parties could be enforced when it had been made in violation of an existing state law. The majority opinion held that the contract should not be enforced because it violated public policy and thus was voidable at either party's discretion. However, Justice Field dissented from this decision on the grounds that enforcing contracts is essential to upholding private rights and maintaining order in society; therefore, he argued that contracts should only be voided if they are illegal or immoral under federal law rather than state laws which may vary from jurisdiction to jurisdiction. He further noted that allowing states to invalidate contracts based on their own laws would lead to uncertainty for citizens who rely upon enforceability of such agreements as well as create confusion among courts trying to interpret them. Ultimately, Justice Field concluded by asserting his belief that any agreement entered into voluntarily by both parties ought not be rendered unenforceable simply because one or more provisions violate local statutes or regulations.