In Brandenburg v. Ohio (395 U.S. 444 ) the United States Supreme Court struck down an Ohio criminal syndicalism statute which penalized "advocating ... the duty, necessity, or propriety of crime, sabotage, violence, or unlawful methods of terrorism as a means of accomplishing industrial or political reform" and "voluntarily assembl[ing] with any society, group, or assemblage of persons formed to teach or advocate the doctrines of criminal syndicalism." The appellant, a leader of the Ku Klux Klan, was convicted under the Ohio criminal syndicalism statute for participating at an organizer's meeting where he expressed derogatory views regarding African-Americans and Jews and alluded to the possibility of "revengeance" being taken by the allegedly suppressed "white, Caucasian race" (id. at 445-446).
In reversing the appellant's conviction and declaring the statute unconstitutional, the Court ruled that the constitutional guarantees of free speech and free press do not permit a state to forbid or proscribe advocacy of the use of force or violence except where such advocacy is directed to and is likely to incite or produce imminent lawless action (id. at 447).
The Court further noted that the right of peaceable assembly is cognate to the rights of free speech and free press and is equally fundamental (id. at 449 n 4.)
Thus, statutes which affect the right of free assembly must also "observe the established distinctions between mere advocacy and incitement to imminent lawless action" (id.). The Ohio criminal syndicalism statute, which punished both advocacy of the use of force or violence to accomplish political or industrial reform and assembly with others to advocate or teach such doctrines, failed to observe these distinctions and therefore was unconstitutional (id.).
The Court reasoned that "the mere abstract teaching ... of the moral propriety or even moral necessity for a resort to force and violence, is not the same as preparing a group for violent action and steeling it to such action" (id. at 448.)