United States v. Arnold is a Supreme Court case from 1942. In this case, the government accused Arnold of breaking a law by buying and selling whiskey that he knew had been illegally made. The Supreme Court ruled that the government had proven its case and that Arnold was guilty of breaking the law. This case is important because it was a landmark decision in the United States that showed that people can be held responsible for things that they knew or should have known were wrong. So if you do something wrong, even if it didn’t seem wrong at the time, you could still be sent to jail.