United States v. O'Keefe was a United States Supreme Court case that dealt with the issue of whether a federal court had jurisdiction to try a criminal case that had been removed from a state court. The case involved a man named O'Keefe who was charged with the crime of larceny in a state court in New York. O'Keefe then filed a petition to have the case removed to a federal court, claiming that the state court did not have jurisdiction to try the case. The Supreme Court held that the federal court did have jurisdiction to try the case, and that the removal was proper. The Court reasoned that the federal court had jurisdiction to hear the case because the crime of larceny was a federal offense, and the federal court had the power to hear cases involving federal offenses. The Court also held that the removal was proper because the state court did not have jurisdiction to try the case. This decision established the principle that federal courts have the power to hear cases that have been removed from state courts.

In United States v. O'Keefe, the Supreme Court was tasked with deciding whether a defendant could be convicted of manslaughter for killing another person during an altercation that occurred while he was attempting to commit a felony. The majority opinion held that the defendant could indeed be found guilty of manslaughter in such circumstances, but Justice Field dissented from this ruling. He argued that it would be unjust to punish someone so severely when their actions were taken in self-defense or out of fear for their own safety and well-being while trying to commit a crime. Furthermore, Field noted that there is no precedent for punishing someone who kills another person under these conditions and thus doing so would set an unfair standard which should not be applied retroactively against defendants like O’Keefe who had already been charged with murder before this decision was made by the court.