Morrill v. Jones 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 violation of a state statute. The case involved a contract between the plaintiff, Morrill, and the defendant, Jones, for the sale of a tract of land. The contract was made in violation of a state statute that prohibited the sale of land without the consent of the state legislature. The Supreme Court held that the state court could not enforce the contract because it was in violation of the state statute. The Court reasoned that the state statute was a valid exercise of the state's police power and that the state had the right to protect its citizens from contracts that were made in violation of the law. The Court also held that the state court could not enforce the contract because it was against public policy. The Court's decision in Morrill v. Jones established the principle that a state court cannot enforce a contract that is in violation of a state statute. This principle has been applied in numerous cases since then and has been used to protect citizens from contracts that are made in violation of the law.

Justice Field delivered the dissenting opinion in Morrill v. Jones, arguing that the majority's decision was wrongfully decided and should be reversed. He argued that a contract between two parties is binding on both of them unless it has been modified or rescinded by mutual agreement or some other legal means. In this case, he believed there had been no such modification or rescission of the original contract between Morrill and Jones; therefore, it remained valid and enforceable against both parties. Furthermore, Justice Field argued that even if there had been an implied rescission due to changes in circumstances since the initial agreement was made - as suggested by the majority - then those changes would have only affected future performance under their contract rather than invalidating its entirety retroactively. Thus, he concluded that Morrill still retained his right to sue for damages arising from breach of their prior contractual obligations despite any intervening events which may have occurred since they originally entered into their agreement with one another.