The First Amendment doesn’t protect statements that are meant to incite listeners to riot or commit other imminent illegal acts, as long as the statements are also likely to have that effect. As the Supreme Court has said, it's obvious that government has the power to prevent or punish speech that displays a clear and present danger of riot or another immediate threat to public safety, peace, or order (Cantwell v. State of Connecticut, 310 U.S. 296 (1940)).
At the same time, however, people have a constitutional right to advocate violence in general, even for abhorrent reasons—like when they allude to killing African Americans as a way to preserve white supremacy (Brandenburg v. Ohio, 395 U.S. 444 (1969)). The same is true when protestors declare—after police have cleared a demonstration—that they’ll take the street back later (Hess v. Indiana, 414 U.S. 105 (1973)).
The First Amendment doesn’t give you the right to make a direct, “true threat” to kill your boss or shoot a judge. But what if you say to a large audience that someone should use their “Second Amendment rights” toward a political opponent? There isn’t a clear, consistent definition of a true threat, but it should be more than political hyperbole or metaphor (“we’re going to kill you at the polls”), a joke, or an impulsive angry comment (Watts v. United States, 394 U.S. 705 (1969)).
In contrast, a true threat is meant to communicate a serious intention to carry out imminent violence against someone. The Supreme Court has said it doesn’t matter if the people making the threat don’t actually plan to carry it out, because barring true threats protects the victims from the fear of violence as well as the actual violence. So intimidating actions like burning a cross can be true threats if they’re meant to make particular individuals or groups of people fear for their lives. (Virginia v. Black, 538 U.S. 343 (2003).)
Other types of speech that aren’t protected by the First Amendment include:
perjury (lying under oath)
plagiarism (copying other people’s writing, art, music, or choreography without their permission)
solicitation (convincing someone else to commit a crime), and
