Violent language is protected by the First Amendment, within limits that the courts have set over the years for speech involving incitement, threats or “fighting words.”
A 1969 Supreme Court decision, Brandenburg v. Ohio, specifies that the “advocacy of the use of force or of law violation” is protected unless “such advocacy is directed to inciting or producing imminent lawless action and is likely to incite or produce such action.”
To fall outside First Amendment protections, the speech in question must constitute a “true threat” rather than “political hyperbole,” as the Court ruled in another 1969 case, Watts v. United States.