Dennis v. United States was a 1951 case in which the United States Supreme Court ruled that the Smith Act, which made it a crime to advocate the violent overthrow of the U.S. government, was constitutional. The case involved Eugene Dennis, the general secretary of the Communist Party USA, and 10 other top party leaders who were convicted under the Smith Act for advocating the overthrow of the U.S. government. The Supreme Court upheld the convictions, holding that the Smith Act was a valid exercise of Congress's power to protect the national security.