Jennisons v. Leonard was a case heard by the United States Supreme Court in 1874. The case involved a dispute between two parties over a contract for the sale of a horse. The plaintiff, Jennisons, had agreed to purchase a horse from the defendant, Leonard, for $100. Jennisons had paid $50 as a down payment and was to pay the remaining $50 when the horse was delivered. However, when the horse was delivered, it was in poor condition and Jennisons refused to pay the remaining $50. Leonard then sued Jennisons for the remaining $50, claiming that the contract was valid and that Jennisons had breached it. The Supreme Court ruled in favor of Leonard, finding that the contract was valid and that Jennisons had breached it. The Court held that the contract was binding and that Jennisons was liable for the remaining $50. The Court also held that Leonard was entitled to damages for the breach of contract. This case established the principle that a contract is binding and that a party who breaches it is liable for damages. It also established that a party who breaches a contract is liable for the full amount of the contract, even if the other party has not yet performed their part of the contract. This case is still cited today as an example of the binding nature of contracts.

In Jennisons v. Leonard, the Supreme Court was asked to decide whether a tenant in possession of land could be held liable for trespass if they continued to occupy the property after their lease had expired. The majority opinion found that since the tenant had not been evicted from the premises and still occupied it, he should be held liable for trespass. However, Justice Field dissented from this decision on two grounds: firstly, that there was no evidence presented at trial showing any intention by either party to terminate or renew the lease; and secondly, that even if such an intention existed it would have been impossible for a jury to determine which party intended what without more information about how long each side expected the tenancy agreement to last. He argued instead that since both parties were equally ignorant of when exactly their agreement ended or began anew then neither should be held responsible for trespassing against one another until such time as clear proof is provided regarding who holds legal title over said property.