I think it only appropriate to quote that Vietnam War era decision somewhat extensively here. In that case, Justice Harlan wrote for the court:
This case may seem at first blush too inconsequential to find its way into our books, but the issue it presents is of no small constitutional significance.
The facts upon which his conviction rests are detailed in the opinion of the Court of Appeal of California, Second Appellate District, as follows:
On April 26, 1968, the defendant was observed in the Los Angeles County Courthouse in the corridor outside of division 20 of the municipal court wearing a jacket bearing the words 'Fuck the Draft' which were plainly visible. There were women and children present in the corridor. The defendant was arrested. The defendant testified that he wore the jacket knowing that the words were on the jacket as a means of informing the public of the depth of his feelings against the Vietnam War and the draft.
(403 U. S. 18) The conviction quite clearly rests upon the asserted offensiveness of the words Cohen used to convey his message to the public. The only "conduct" which the State sought to punish is the fact of communication. Thus, we deal here with a conviction resting solely upon "speech," cf. Stromberg v. California, 283 U. S. 359 (1931), not upon any separately identifiable conduct which allegedly was intended by Cohen to be perceived by others as expressive of particular views but which, on its face, does not necessarily convey any message, and hence arguably could be regulated without effectively repressing Cohen's ability to express himself. Cf. United States v. O'Brien, 391 U. S. 367 (1968). Further, the State certainly lacks power to punish Cohen for the underlying content of the message the inscription conveyed. At least so long as there is no showing of an intent to incite disobedience to or disruption of the draft, Cohen could not, consistently with the First and Fourteenth Amendments, be punished for asserting the evident position on the inutility or immorality of the draft his jacket reflected. Yates v. United States, 354 U. S. 298 (1957).
(403 U. S. 19-21) [A]s it comes to us, this case cannot be said to fall within those relatively few categories of instances where prior decisions have established the power of government to deal more comprehensively with certain forms of individual expression simply upon a showing that such a form was employed. This is not, for example, an obscenity case. [emphasis added] Whatever else may be necessary to give rise to the States' broader power to prohibit obscene expression, such expression must be, in some significant way, erotic. Roth v. United States, 354 U. S. 476 (1957). It cannot plausibly be maintained that this vulgar allusion to the Selective Service System would conjure up such psychic stimulation in anyone likely to be confronted with Cohen's crudely defaced jacket.
This Court has also held that the States are free to ban the simple use, without a demonstration of additional justifying circumstances, of so-called "fighting words," those personally abusive epithets which, when addressed to the ordinary citizen, are, as a matter of common knowledge, inherently likely to provoke violent reaction. Chaplinsky v. New Hampshire, 315 U. S. 568 (1942). While the four-letter word displayed by Cohen in relation to the draft is not uncommonly employed in a personally provocative fashion, in this instance it was clearly not "directed to the person of the hearer." Cantwell v. Connecticut, 310 U. S. 296, 310 U. S. 309 (1940). No individual actually or likely to be present could reasonably have regarded the words on appellant's jacket as a direct personal insult. Nor do we have here an instance of the exercise of the State's police power to prevent a speaker from intentionally provoking a given group to hostile reaction. Cf. Feiner v. New York, 340 U. S. 315 (1951); Termniello v. Chicago, 337 U. S. 1 (1949). There is, as noted above, no showing that anyone who saw Cohen was, in fact, violently aroused, or that appellant intended such a result.
Finally, in arguments before this Court, much has been made of the claim that Cohen's distasteful mode of expression was thrust upon unwilling or unsuspecting viewers, and that the State might therefore legitimately act as it did in order to protect the sensitive from otherwise unavoidable exposure to appellant's crude form of protest. Of course, the mere presumed presence of unwitting listeners or viewers does not serve automatically to justify curtailing all speech capable of giving offense. See, e.g., Organization for a Better Austin v. Keefe, 402 U. S. 415 (1971). While this Court has recognized that government may properly act in many situations to prohibit intrusion into the privacy of the home of unwelcome views and ideas which cannot be totally banned from the public dialogue, e.g., Rowan v. Post Office Dept., 397 U. S. 728 (1970), we have at the same time consistently stressed that "we are often captives' outside the sanctuary of the home and subject to objectionable speech." Id. at 397 U. S. 738. The ability of government, consonant with the Constitution, to shut off discourse solely to protect others from hearing it is, in other words, dependent upon a showing that substantial privacy interests are being invaded in an essentially intolerable manner. [emphasis added] Any broader view of this authority would effectively empower a majority to silence dissidents simply as a matter of personal predilections.
[403 U. S. 24-25] The constitutional right of free expression is powerful medicine in a society as diverse and populous a ours. It is designed and intended to remove governmental restraints from the arena of public discussion, putting the decision as to what views shall be voiced largely into the hands of each of us, in the hope that use of such freedom will ultimately produce a more capable citizenry and more perfect polity and in the belief that no other approach would comport with the premise of individual dignity and choice upon which our political system rests. See Whitney v. California, 274 U. S. 357, 274 U. S. 375-377 (1927) (Brandeis, J., concurring).
... We cannot lose sight of the fact that, in what otherwise might seem a trifling and annoying instance of individual distasteful abuse of a privilege, these fundamental societal values are truly implicated. That is why "[w]holly neutral futilities . . . come under the protection of free speech as fully as do Keats' poems or Donne's sermons," Winters v. New York, 333 U. S. 507, 333 U. S. 528 (1948) (Frankfurter, J., dissenting), and why, "so long as the means are peaceful, the communication need not meet standards of acceptability," Organization for a Better Austin v. Keefe, 402 U. S. 415, 402 U. S. 419 (1971).
... while the particular four-letter word being litigated here is perhaps more distasteful than most others of its genre, it is nevertheless often true that one man's vulgarity is another's lyric. Indeed, we think it is largely because governmental officials cannot make principled distinctions in this area that the Constitution leaves matters of taste and style so largely to the individual.
Additionally, we cannot overlook the fact, because it is well illustrated by the episode involved here, that much linguistic expression serves a dual communicative function: it conveys not only ideas capable of relatively precise, detached explication, but otherwise inexpressible emotions as well. In fact, words are often chosen as much for their emotive as their cognitive force. ... Indeed, as Mr. Justice Frankfurter has said,
[o]ne of the prerogatives of American citizenship is the right to criticize public men and measures -- and that means not only informed and responsible criticism, but the freedom to speak foolishly and without moderation.
Baumgartner v. United States, 322 U. S. 665, 322 U. S. 673-674 (1944).