A true threat is a threatening communication that can be prosecuted under the law. It is distinct from a threat that is made in jest. The U.S. Supreme Court has held that true threats are not protected under the U.S. Constitution based on three justifications: preventing fear, preventing the disruption that follows from that fear, and diminishing the likelihood that the threatened violence will occur. There is some concern that even satirical speech could be regarded as a "true threat" due to concern over terrorism.
The true threat doctrine was established in the 1969 Supreme Court case Watts v. United States. In that case, an eighteen-year-old male was convicted in a Washington, D.C. District Court for violating a statute prohibiting persons from knowingly and willfully making threats to harm or kill the President of the United States. The conviction was based on a statement made by Watts, in which he said, "[i]f they ever make me carry a rifle the first man I want to get in my sights is L.B.J." Watts appealed, leading to the Supreme Court finding the statute constitutional on its face, but reversing the conviction of Watts.
In reviewing the lower court's analysis of the case, the Court noted that "a threat must be distinguished from what is constitutionally protected speech." The Court recognized that "uninhibited, robust, and wideopen" political debate can at times be characterized by "vehement, caustic, and sometimes unpleasantly sharp attacks on government and public officials." In light of the context of Watts' statement - and the laughter that it received from the crowd - the Court found that it was more "a kind of very crude offensive method of stating a political opposition to the President" than a "true threat."  In so holding, the Court established that there is a "true threat" exception to protected speech, but also that the statement must be viewed in its context and distinguished from protected hyperbole. The opinion, however, stopped short of defining precisely what constituted a "true threat." 
- Toward an Improved True Threat Doctrine for Student Speakers; Stanner, Andrew P., 81, N.Y.U. L. Rev., 2006, p. 385
- Gilbert, Lauren (2003–2004), Mocking George: Political Satire as True Threat in the Age of Global Terrorism, 58, U. Miami L. Rev., p. 843
- Is the True Threats Doctrine Threatening the First Amendment? Planned Parenthood of the Columbia/Willamette, Inc. v. American Coalition of Life Activists Signals the Need To Remedy an Inadequate Doctrine; Weiss, Lori, 72, Fordham L. Rev., 2004, p. 1283