sedition (sĭdĭˈshən) [key], in law, acts or words tending to upset the authority of a government. The scope of the offense was broad in early common law, which even permitted prosecution for a remark insulting to the king. Although there have been several statutes in the United States forbidding seditious utterances and writings, the protection guaranteed to speech and press by the First Amendment to the Constitution has made them difficult to enforce except during periods of great national stress. The Sedition Act of 1798 generated so much opposition (see Alien and Sedition Acts) that similar statutes were not enacted until the 20th cent. During World War I the Espionage Act (1917) and the Sedition Act (1918) punished speeches and writings that interfered with the war effort or caused contempt for the government. Vaguely worded and broadly interpreted, they resulted in over 2,000 prosecutions, mostly against radicals and the radical press. The Smith Act of 1940, restricted in scope to the advocacy of violence against the government, was invoked only infrequently during World War II, though it was later used successfully to prosecute Communist party leaders, as in Dennis v. United States (1951). The libel decision of Sullivan v. New York Times (1964), by granting special protection to criticism of public officials, largely eliminated what remained of the crime of sedition in the United States.