Chaplinsky v. New Hampshire

From Conservapedia

In Chaplinsky v. New Hampshire, 315 U.S. 568, 571-72 (1942), the U.S. Supreme Court held that "[t]here are certain well-defined and narrowly limited classes of speech, the prevention and punishment of which has never been thought to raise any Constitutional problem." Specifically, this decision declared "fighting words" to be outside the scope of the First Amendment when the words are likely immediately to incite a violent response.

This unanimous decision, written by Justice Murphy, is one of the most-often cited precendents (3856 references in Shepards citation service as of August 27, 2007).