Hill v. Sumner was a case heard by the Supreme Court of the United States in 1876. The case involved a dispute between two parties over a contract for the sale of a horse. The plaintiff, Hill, had agreed to purchase a horse from the defendant, Sumner, for $100. Hill paid the $100, but Sumner refused to deliver the horse. Hill then sued Sumner for breach of contract. The Supreme Court held that Hill was entitled to recover the $100 he had paid for the horse, plus damages for the breach of contract. The Court reasoned that the contract was valid and enforceable, and that Sumner had breached it by refusing to deliver the horse. The Court also held that Hill was entitled to damages for the breach of contract, as he had been deprived of the benefit of the bargain. The decision in Hill v. Sumner established the principle that a party who breaches a contract is liable for damages, and that the damages should be sufficient to put the injured party in the same position as if the contract had been performed. This principle has been applied in numerous cases since then, and is still an important part of contract law today.

In the case of Hill v. Sumner, Justice Field wrote a dissenting opinion in which he argued that the majority's decision was wrongfully based on an interpretation of state law rather than federal law. He believed that it should have been determined by federal common law instead and noted that there were no cases to support the majority's ruling. Furthermore, he argued that Congress had not intended for states to be able to interfere with contracts made between citizens from different states and thus any such interference would be unconstitutional under Article IV Section 1 of the Constitution. In conclusion, Justice Field disagreed with the majority opinion because it relied too heavily on state laws while disregarding federal common law as well as constitutional provisions protecting interstate commerce agreements from being interfered with by individual states.