Ager v. Murray was a United States Supreme Court case that addressed 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, Ager and Murray, in which Ager agreed to pay Murray a certain sum of money in exchange for a certain amount of land. The contract was made in the state of New York, but Murray brought suit in the state of Pennsylvania to enforce the contract. The Supreme Court held that the state court in Pennsylvania did not have the authority to enforce the contract because it was made in another state. The Court reasoned that the contract was made in New York and was therefore subject to the laws of that state. The Court further held that the state of Pennsylvania could not enforce a contract that was made in another state, as this would be a violation of the Full Faith and Credit Clause of the United States Constitution. The Court's decision in Ager v. Murray established the principle that a state court cannot enforce a contract that was made in another state. This decision has been cited in numerous subsequent cases and has become an important part of the law of contracts.

Justice Field delivered the dissenting opinion in Ager v. Murray, arguing that the majority's decision was contrary to both precedent and sound legal reasoning. He argued that a contract between two parties should be enforced according to its terms unless it is found to be illegal or against public policy. In this case, he argued that there was no evidence of illegality or public policy violation; therefore, the contract should have been enforced as written. Furthermore, Justice Field noted that if one party had not performed their obligations under the agreement then they could have sued for damages but not sought rescission of the entire agreement as they did here. Finally, he concluded by noting his disagreement with allowing courts to rewrite contracts based on what they believe is fair and equitable when there is no evidence of fraud or other wrongdoing by either party involved in making such an agreement.