William J. Brennan Freedom Of Speech Quotations

Debate on public issues should be uninhibited, robust and wide-open and that...may well include vehement, caustic, and sometimes unpleasantly sharp attacks on government and public officials.

Authoritative interpretations of the First Amendment guarantees have consistently refused to recognize an exception for any test of truth whether administered by judges, juries, or administrative officials and especially one that puts the burden of proving truth on the speaker.