American Law recognizes eight classes of exceptions to free speech:
1) Incitement. Although a person should be free to express a belief, including advocating the use of violence, a person is not free to incite a person or persons in to direct and immediate violence.
2) False statements. Although a person is free to lie, a person is not free to commit fraud, libel or slander.
3) Obscenity. Controversial, but recognized as a legitimate exception
4) Child pornography. Less controversial, although there are debates about how works of fiction should be treated.
5) Fighting words. Similar but less direct than incitement. Problematic, but still on the books.
6) Threats. Assault, a threat uttered with the apparent means to carry it out, is not protected speech.
7) Proprietary expression. Copyrighted material is owned by the artists who created it.
8) Commercial speech. Commercial speech (i.e. advertising) is subject to far more restriction than individual expression.
While I don't expect that people will universally embrace all of these exceptions, I do think that there are many criminal behaviours that are limitations on "complete" freedom of speech, and properly so.
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--James