Whatever theoretical merit there may be to the argument that there is a "right" to rebellion against dictatorial governments is without force where the existing structure of the government provides for peaceful and orderly change. We reject any principle of governmental helplessness in the face of preparation for revolution, which principle, carried to its logical conclusion, must lead to anarchy.Justices Douglas and Black dissented, saying that mere words were not a sufficient danger to justify being outlawed.
The Supreme Court finally endorsed the First Amendment right to engage in revolutionary speech in the 1969 case of Brandenburg v. Ohio. This case differed from its predecessors in that it involved right-wing revolutionaries, specifically, a Ku Klux Klan rally, but this does not appear to be a significant difference. The Ku Klux Klan was as reviled and outside the mainstream in 1969 as Anarchists or Radical Socialists during WWI or the Communists in the 1950's. Perhaps significantly, several members of the rally had guns. No guns were mentioned in any of the earlier cases. Though armed, but rally appears to have been quite small, perhaps with as few as a dozen participants, but they invited the press and one of them said, "We are marching on Congress July the Fourth, four hundred thousand strong." The participants were charged and convicted under Ohio's "criminal syndicalism" statute against advocating "crime, sabotage, violence, or unlawful methods of terrorism as a means of accomplishing industrial or political reform."
This time the Court expressly overruled its decision in Whitney v. California that upheld criminal syndicalism statutes and held that advocacy of political violence is constitutionally protected free speech. Even then, however, the Supreme Court distinguished between "mere advocacy" (constitutionally protected) and "incitement to imminent lawless conduct" (not protected). And it favorably cited its prior case of Noto v. U.S.* 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."
Justices Douglas and Black wrote a concurrence, going over the general history of First Amendment jurisprudence, and then rejected the entire "clear and present danger" test altogether:
When one reads the opinions closely and sees when and how the "clear and present danger" test has been applied, great misgivings are aroused. First, the threats were often loud, but always puny, and made serious only by judges so wedded to the status quo that critical analysis made them nervous. Second, the test was so twisted and perverted in Dennis as to make the trial of those teachers of Marxism an all-out political trial which was part and parcel of the cold war that has eroded substantial parts of the First Amendment.He argued, instead, that only immediate, actual incitement of violence should be prosecuted.
*Noto held that membership in the Communist Party could not be punished because the Communist Party advocated violent revolution only as an abstract doctrine and not by "the use of language reasonably and ordinarily calculated to incite persons to action, immediately or in the future."