From the Free Speech Museum (

'In the case of Chaplinsky v. New Hampshire, the Supreme Court recognized a First Amendment exception for "fighting words", which it described as "those which by their very utterance 1 inflict injury or 2 tend to incite an immediate breach of the peace." In the decades since this 1940 decision, the Court has limited its effects to the most challenging and confrontational of words spoken in a face to face encounter and likely to lead to immediate fighting.'