Appellant, a Ku Klux Klan leader, was convicted under the Ohio Criminal Syndicalism statute for "advocat[ing] . . . the duty, necessity, or propriety of crime, sabotage, violence, or unlawful methods of terrorism as a means of accomplishing industrial or political reform" and for "voluntarily assembl[ing] with any society, group or assemblage of persons formed to teach or advocate the doctrines of criminal syndicalism." Neither the indictment nor the trial judge's instructions refined the statute's definition of the crime in terms of mere advocacy not distinguished from incitement to imminent lawless action. Held: Since the statute, by its words and as applied, purports to punish mere advocacy and to forbid, on pain of criminal punishment, assembly with others merely to advocate the described type of action, it falls within the condemnation of the First and Fourteenth Amendments. Freedoms of speech and press do not permit a State to forbid advocacy of the use of force or of law violation except where such advocacy is directed to inciting or producing imminent lawless action and is likely to incite or produce such action.