Isaac Underhill v. John M. Herndon was a case heard by the United States Supreme Court in 1869. The case involved a dispute between two parties over a contract for the sale of a steamboat. Underhill, the plaintiff, had contracted with Herndon, the defendant, to purchase a steamboat for $2,000. Underhill paid the full amount, but Herndon refused to deliver the boat. Underhill then sued Herndon for breach of contract. The Supreme Court ruled in favor of Underhill, finding that Herndon had breached the contract and was liable for damages. The Court held that the contract was valid and enforceable, and that Underhill was entitled to recover the full amount of the purchase price, plus interest. The Court also held that Herndon was liable for any damages caused by his breach of contract. The decision in this case established the principle that a contract is binding and enforceable, and that a party who breaches a contract is liable for damages. This case also established the principle that a party who breaches a contract is liable for any damages caused by the breach. This case is still cited today as an example of the importance of upholding contracts and the consequences of breaching them.

In the case of Issac Underhill v. John M. Herndon, the Supreme Court was tasked with determining whether a contract between two parties was valid and enforceable under state law. The majority opinion held that it was not, as there had been no consideration given for its formation or performance. However, Justice Field dissented from this ruling on the grounds that an agreement to pay money in exchange for services rendered is sufficient consideration to make a contract binding and enforceable under state law. He argued that if such agreements were not considered legally binding then people would be discouraged from entering into contracts due to fear of being unable to recover what they are owed should one party fail to fulfill their obligations. Furthermore, he noted how courts have long recognized verbal promises as legally binding when supported by evidence of payment or other forms of consideration and thus concluded that this particular agreement should also be upheld as valid and enforceable despite lacking any written documentation attesting its existence