Tappan v. Beardsley was a United States Supreme Court case that was decided in 1870. The case involved a dispute between two parties over a contract for the sale of a steamboat. The plaintiff, Tappan, had entered into a contract with the defendant, Beardsley, to purchase a steamboat for $2,000. Beardsley had agreed to deliver the boat to Tappan, but failed to do so. Tappan then sued Beardsley for breach of contract. The Supreme Court held that Beardsley was liable for breach of contract. The Court found that Beardsley had failed to fulfill his obligations under the contract and that Tappan was entitled to damages. The Court also held that Beardsley was liable for any losses that Tappan had suffered as a result of the breach. The decision in Tappan v. Beardsley established the principle that a party who breaches a contract is liable for any losses that the other party suffers as a result of the breach. This principle has been applied in numerous cases since then and is still an important part of contract law today.

In Tappan v. Beardsley, the United States Supreme Court was asked to decide whether a contract between two parties should be enforced when it had been made under duress. The majority opinion held that the contract could not be enforced because of its coercive nature and that any benefit received by one party as a result of the agreement must be returned. However, Justice Field dissented from this decision on several grounds. He argued that while coercion may have been used in making the agreement, there was no evidence to suggest either party intended for it to remain unenforceable or invalidated by such means; rather, he believed both parties were fully aware of their rights and obligations under the terms of their arrangement and thus should not suffer any detriment due solely to its formation through duress. Furthermore, Field reasoned that if contracts formed under similar circumstances were deemed void ab initio then all agreements would become subject to challenge based upon claims of coercion which would lead only chaos in commercial transactions throughout society at large.