During the Great War the frenzy to control opposition to war resulted in several efforts to limit freedom of speech. State legislation, gubernatorial proclamations, and municipal ordinances had the immediate impact of controlling dissent, but the cessation of the war ended such activities. Congressional passage of the Espionage Act in 1917 changed this dynamic and left behind a long-term legacy. Several cases argued on behalf of defendants imprisoned for opposing the nation’s war effort arrived at the United States Supreme Court for review. Justices for the first time defined the boundaries of the First Amendment by arguing that expressions could pose a “clear and present danger” during a national crisis. This interpretation has led to passage of recent legislation, including the USA PATRIOT Act, and has been used to justify the arrest of individuals who leak sensitive information.