Which U.S. Supreme Court case established the 'clear and present danger' test?

Which U.S. Supreme Court case established the “clear and present danger” test? Schenck v. United States established the phrase and doctrine in 1919.

The case arose during World War I, when Socialist Party officials Charles Schenck and Elizabeth Baer distributed leaflets urging men to resist the military draft. The defendants were prosecuted under the Espionage Act of 1917. The Supreme Court unanimously upheld their convictions on March 3, 1919.

Justice Oliver Wendell Holmes Jr. wrote that speech could be punished when used in circumstances creating a “clear and present danger” of substantive evils Congress had authority to prevent. His opinion used the famous example of falsely shouting fire in a theater, while emphasizing that context and proximity mattered.

The doctrine was not a permanent free-speech rule. Later decisions narrowed and criticized it, and Brandenburg v. Ohio replaced it with the more protective “imminent lawless action” test in 1969. Gitlow, Abrams, and Brandenburg are important neighboring cases, but Schenck is the canonical answer to the question asking which case established the clear-and-present-danger test.