Parsons v. Jackson was a United States Supreme Court case that dealt with the issue of whether a contract between two parties was valid. The case involved two parties, Parsons and Jackson, who had entered into a contract for the sale of a horse. Parsons had agreed to pay Jackson $100 for the horse, and Jackson had agreed to deliver the horse to Parsons. However, Jackson failed to deliver the horse, and Parsons sued for breach of contract. The Supreme Court held that the contract between Parsons and Jackson 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 illegal or against public policy, and that it was not too vague or uncertain to be enforced. The Court ultimately held that Parsons was entitled to recover the $100 he had agreed to pay for the horse, plus damages for the breach of contract. The Court also held that Jackson was liable for any damages that Parsons had suffered as a result of the breach. This case established the principle that contracts are enforceable and that parties must be held accountable for any breach of contract.

In Parsons v. Jackson, the United States Supreme Court was tasked with determining whether a contract between two parties could be enforced when one of the parties had died before it was fully executed. The majority opinion held that such contracts were not enforceable because they lacked consideration and mutuality of obligation. Justice Field dissented from this decision, arguing that there should be an exception to this rule in cases where both parties have already performed some part of their obligations under the contract prior to death or incapacity. He argued that if one party has already given something in exchange for what is promised by the other party, then it would be unjust to deny them enforcement simply because they are unable to complete their end of the bargain due to death or incapacity.