This circular was introduced as evidence in Schenck v. United States. Charles Schenck was a prominent socialist who was convicted under the Espionage Act for encouraging men to resist the draft. Justice Oliver Wendell Holmes wrote the unanimous opinion stating that Schenk’s actions constituted “clear and present danger”.
“Wake up America! Your Liberties are in Danger!” 1919
National Archives, Records of the Supreme Court of the United States