Reed v. Gardner was a United States Supreme Court case that addressed the issue of whether a state court had the authority to modify a contract between two parties. The case involved a dispute between two parties, Reed and Gardner, over a contract for the sale of a tract of land. Gardner had agreed to sell the land to Reed for a certain sum of money, but Reed failed to make the payments as agreed. Gardner then sought to modify the contract in order to receive the money he was owed. The Supreme Court held that the state court did not have the authority to modify the contract. The Court reasoned that the contract was a private agreement between two parties and that the state court did not have the power to interfere with the terms of the contract. The Court also noted that the contract was not a matter of public policy and that the state court did not have the authority to modify the contract. The Court's decision in Reed v. Gardner established that state courts do not have the authority to modify private contracts between two parties. This decision has been cited in numerous cases since then, and it has been used to support the principle that state courts cannot interfere with the terms of private contracts.

Justice Field delivered the dissenting opinion in Reed v. Gardner, arguing that the majority's decision was a misinterpretation of the law and an unjust result for both parties. He argued that under California law, which governed this case, a judgment creditor had no right to levy on property owned by their debtor prior to obtaining a writ of execution from the court. The fact that Mr. Gardner had obtained title to his land before he owed money did not change this rule; as such, Justice Field believed it was wrong for Mrs. Reed to be able to take possession of Mr. Gardner's land without first obtaining an order from the court authorizing her seizure of it through legal process or payment made voluntarily by him in satisfaction of his debt obligation with her husband’s estate.. Furthermore, Justice Field noted that even if Mrs. Reed were legally entitled to seize Mr. Gardener’s property without going through proper legal channels she still should have been required pay fair market value for its use since she received benefit from it while holding onto it during litigation proceedings against him - something which would not have occurred if she had gone through proper legal channels instead and obtained permission from a court beforehand allowing her access rights over said property until such time as any debts due were paid off in full or otherwise satisfied according to terms agreed upon between all involved parties at some point thereafter