Farlow v. Kelley was a United States Supreme Court case that dealt with the issue of whether a state court could enforce a contract that was made in another state. The case involved a contract between two parties, Farlow and Kelley, in which Farlow agreed to pay Kelley a certain amount of money for the sale of a piece of property. The contract was made in the state of New York, but Kelley attempted to enforce the contract in the state of Massachusetts. The Supreme Court held that the contract was valid and enforceable in Massachusetts. The Court reasoned that the contract was valid under the Full Faith and Credit Clause of the United States Constitution, which requires states to give full faith and credit to the public acts, records, and judicial proceedings of other states. The Court also held that the contract was valid under the law of the state of New York, which allowed for the enforcement of contracts made in other states. The Court's decision in Farlow v. Kelley established that contracts made in one state can be enforced in another state, provided that the contract is valid under the law of the state in which it was made. This decision has been cited in numerous subsequent cases and has become an important part of contract law in the United States.

In Farlow v. Kelley, the United States Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a non-resident against another non-resident in which the cause of action arose outside of that state's borders. The majority opinion held that such jurisdiction did not exist and thus dismissed the case. Justice Field dissented from this decision, arguing that states should have authority to adjudicate cases involving parties who are both citizens or residents of other states when those cases arise out of transactions occurring within their own boundaries. He argued further that if this power were denied then it would be difficult for individuals living in one state to obtain justice from courts located elsewhere due to jurisdictional issues and lack of access to witnesses or evidence needed for their defense. As such, he concluded that allowing each state court jurisdiction over matters arising within its own borders was necessary in order for justice to be served fairly and efficiently across all jurisdictions throughout the country.