Clear and present danger was a doctrine adopted by the Supreme Court of the United States to determine under what circumstances limits can be placed on First Amendment freedoms of speech, press, or assembly. Created by Justice Oliver Wendell Holmes Jr. to refine the bad tendency test, it was never fully adopted and both tests were ultimately replaced in 1969 with Brandenburg v. Ohio's "imminent lawless action" test.
In United States law, the bad tendency principle was a test that permitted restriction of freedom of speech by government if it was believed that a form of speech had a sole tendency to incite or cause illegal activity. The principle, formulated in Patterson v. Colorado (1907), was seemingly overturned with the "clear and present danger" principle used in the landmark case Schenck v. United States (1919), as stated by Justice Oliver Wendell Holmes Jr. Yet eight months later, at the start of the next term in Abrams v. United States (1919), the Court again used the bad tendency test to uphold the conviction of a Russian immigrant who published and distributed leaflets calling for a general strike and otherwise advocated revolutionary, anarchist, and socialist views. Holmes dissented in Abrams, explaining how the clear and present danger test should be employed to overturn Abrams' conviction. The re-emergence of the bad tendency test resulted in a string of cases, after Abrams, employing that test, including Whitney v. California (1927), where a woman was convicted simply because of her association with the Communist Party. The court ruled unanimously that although she had not committed any crimes, her relationship with the Communists represented a "bad tendency" and thus was unprotected. The "bad tendency" test was finally overturned in Brandenburg v. Ohio (1969) and was replaced by the "imminent lawless action" test.
Schenck v. United States, 249 U.S. 47 (1919), was a landmark decision of the U.S. Supreme Court concerning enforcement of the Espionage Act of 1917 during World War I. A unanimous Supreme Court, in an opinion by Justice Oliver Wendell Holmes Jr., concluded that Charles Schenck and other defendants, who distributed flyers to draft-age men urging resistance to induction, could be convicted of an attempt to obstruct the draft, a criminal offense. The First Amendment did not protect Schenck from prosecution, even though, "in many places and in ordinary times, the defendants, in saying all that was said in the circular, would have been within their constitutional rights. But the character of every act depends upon the circumstances in which it is done." In this case, Holmes said, "the words used are used in such circumstances and are of such a nature as to create a clear and present danger that they will bring about the substantive evils that Congress has a right to prevent." Therefore, Schenck could be punished.
The Court followed this reasoning to uphold a series of convictions arising out of prosecutions during wartime, but Holmes began to dissent in the case of Abrams v. United States, insisting that the Court had departed from the standard he had crafted for them and had begun to allow punishment for ideas. In 1969, Schenck was largely overturned by Brandenburg v. Ohio, which limited the scope of speech that the government may ban to that directed to and likely to incite imminent lawless action (e.g. a riot).