Fink v. O'Neil 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, Fink and O'Neil, in which Fink agreed to pay O'Neil a certain amount of money for the sale of a piece of property. The contract was made in the state of New York, but O'Neil brought suit in the state of Pennsylvania to enforce the contract. The Supreme Court held that the state court in Pennsylvania had the authority to enforce the contract, even though it was made in another state. The Court reasoned that the contract was valid and enforceable 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 noted that the contract was not contrary to the public policy of Pennsylvania, and thus the state court had the authority to enforce it. In conclusion, the Supreme Court held that the state court in Pennsylvania had the authority to enforce the contract between Fink and O'Neil, even though it was made in another state. The Court reasoned that the contract was valid and enforceable under the Full Faith and Credit Clause of the United States Constitution, and that it was not contrary to the public policy of Pennsylvania.

Justice Field dissented in the case of Fink v. O'Neil, arguing that a state court had no jurisdiction to hear and determine an action brought by a citizen of another state against one who was also a citizen of another state. He argued that under Article III Section 2 Clause 1 of the United States Constitution, such cases must be heard in federal courts. He noted that this clause is not limited to diversity cases but applies to all controversies between citizens from different states regardless if they are based on contract or tort claims. Justice Field further argued that Congress has exclusive power over matters concerning interstate commerce and thus it should have been up to them as opposed to individual states whether or not these types of suits could be tried in their respective courts.