Willard v. Tayloe was a United States Supreme Court case that dealt with the issue of whether a contract between two parties was valid. The case involved a contract between William Willard and John Tayloe, in which Willard agreed to pay Tayloe a certain sum of money in exchange for a tract of land. Willard paid the money, but Tayloe refused to convey the land. Willard then sued Tayloe for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court noted that the contract was supported by consideration, meaning that both parties had given something of value in exchange for the other's promise. The Court also noted that the contract was not against public policy, as it did not involve any illegal activity. The Court ultimately held that Willard was entitled to the land, and that Tayloe was liable for breach of contract. The Court ordered Tayloe to convey the land to Willard, and to pay him damages for the breach. This case established the principle that contracts are binding and enforceable, and that parties must fulfill their obligations under the contract.

In Willard v. Tayloe, the Supreme Court was tasked with deciding whether a contract between two parties could be enforced if it had been made in violation of an existing law. The majority opinion held that such contracts were not enforceable and should be declared void by the court. However, Justice Field dissented from this decision on the grounds that there is no general principle which declares all contracts illegal when they are contrary to public policy or statute law; rather, each case must be judged on its own merits and circumstances. He argued that while some contracts may indeed violate public policy or statute laws, others can still stand as valid agreements between two parties who have willingly entered into them without any intention of defrauding either party involved or violating any existing laws. Furthermore, he asserted that courts should not interfere with private transactions unless absolutely necessary since doing so would undermine citizens' confidence in their ability to make binding agreements amongst themselves without fear of judicial interference.