United States v. Mynders was a United States Supreme Court case that was decided in 1870. The case involved a dispute between the United States and a former Confederate soldier, William Mynders, over the ownership of a piece of property in Tennessee. Mynders had purchased the property from a Confederate officer during the Civil War, and the United States argued that the sale was invalid because it had not been approved by the United States government. The Supreme Court ruled in favor of the United States, holding that the sale was invalid because it had not been approved by the United States government. The Court reasoned that the United States had a superior right to the property, as it had been seized by the Union army during the war. The Court also held that the sale was invalid because it had been made without the consent of the United States government. The decision in United States v. Mynders established the principle that the United States government has a superior right to property seized during the Civil War, and that any sale of such property must be approved by the United States government. This decision has been cited in numerous subsequent cases involving the ownership of property seized during the Civil War.

In United States v. Mynders, the Supreme Court considered whether a federal court had jurisdiction to hear an appeal from a decision of the Commissioner of Patents in denying a patent for an invention. The majority opinion held that such appeals were not within the scope of federal judicial power and thus could not be heard by any court other than Congress itself. Justice Field dissented, arguing that it was well established law that when Congress has given exclusive authority to decide certain matters to executive officers or departments, then those decisions are subject to review by courts if they involve questions of law or fact which can be determined judicially. He argued further that since patents involved both legal and factual issues, it was appropriate for them to be reviewed by courts as part of their duty under Article III Section 2 Clause 1 (the "judicial power" clause)of the Constitution.