Dowell v. Mitchell was a United States Supreme Court case that addressed 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 two parties, Dowell and Mitchell, in which Dowell agreed to pay Mitchell a certain amount of money in exchange for a deed to a piece of property. The contract was made in violation of a state statute that prohibited the sale of property without a license. The Supreme Court held that the state court could not enforce the contract because it was made 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 noted that the state had the right to protect its citizens from contracts that were made without proper consideration. The Court's decision in Dowell v. Mitchell established that a state court could not enforce a contract that was made in violation of a state statute. This decision has been cited in numerous cases since then and has been used to support the idea that a state court cannot enforce a contract that is made in violation of the law.

Justice Field delivered the dissenting opinion in Dowell v. Mitchell, 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, regardless of any subsequent changes to state law or regulations. In this case, he argued that when Dowell entered into an agreement with Mitchell for the sale of certain lands in 1867, it created a valid and enforceable contract between them which could not be altered by subsequent legislation passed by Congress or other acts taken by either party after its formation. Furthermore, Justice Field noted that even if there had been some ambiguity as to whether or not such contracts were still legally binding under existing laws at the time they were formed (which he did not believe was true), then those ambiguities should have been resolved in favor of upholding their validity since they are presumed to be valid until proven otherwise. As such, Justice Field concluded his dissent stating that because no evidence had been presented showing why these contracts should now be held invalid due to changed circumstances since their formation - nor any proof demonstrating how allowing them would cause harm - then they must remain enforced according to their original terms and conditions as agreed upon by both parties at the time they were made.