United States v. Cooper was a United States Supreme Court case that addressed the issue of whether a defendant could be convicted of a crime if the indictment was not returned within the time period prescribed by the applicable statute of limitations. The Court held that the defendant could not be convicted of the crime because the indictment was not returned within the time period prescribed by the statute of limitations. The case involved a defendant, Cooper, who was charged with a crime in the United States District Court for the Eastern District of Arkansas. The indictment was returned more than three years after the alleged offense was committed, which was beyond the two-year statute of limitations for the offense. Cooper moved to quash the indictment on the grounds that it was returned beyond the statute of limitations. The District Court denied the motion and Cooper was convicted. The Supreme Court reversed the conviction, holding that the indictment was not returned within the time period prescribed by the statute of limitations and, therefore, the defendant could not be convicted of the crime. The Court reasoned that the statute of limitations was a substantive right that could not be waived by the defendant and that the indictment was void if it was returned beyond the time period prescribed by the statute of limitations. The Court also noted that the statute of limitations was intended to protect defendants from being prosecuted for crimes that were committed long ago and that the purpose of the statute would be defeated if the defendant could be convicted despite the fact that the indictment was returned beyond the time period prescribed by the statute of limitations.

In United States v. Cooper, the Supreme Court was asked to decide whether a federal statute that allowed for criminal prosecution of individuals who had failed to pay taxes on distilled spirits applied retroactively. The majority opinion held that the statute did apply retroactively and thus affirmed the conviction of William Cooper, who had been convicted under this law for failing to pay taxes on distilled spirits he owned prior to its enactment. Justice Field dissented from this decision and argued that Congress could not constitutionally pass a law with retrospective effect unless it explicitly stated so in clear language within the text of the legislation itself. He further argued that since there was no such explicit statement in this particular case, then applying it retrospectively would be an unconstitutional exercise of power by Congress as well as an infringement upon individual rights protected by due process clauses found in both state constitutions and common law principles.