During World War I, Schenck mailed circulars to draftees. The circulars suggested that the draft was a monstrous wrong motivated by the capitalist system. The circulars urged "Do not submit to intimidation" but advised only peaceful action such as petitioning to repeal the Conscription Act. Schenck was charged with conspiracy to violate the Espionage Act by attempting to cause insubordination in the military and to obstruct recruitment.

Are Schenck's actions (words, expression) protected by the free speech clause of the First Amendment?

Holmes, speaking for a unanimous Court, concluded that Schenck is not protected in this situation. The character of every act depends on the circumstances. "The question in every case is whether 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." During wartime, utterances tolerable in peacetime can be punished.

Source

• http://www.oyez.org/cases/1901-1939/1918/1918_437#sort=ideology