tution does not protect libelous publications. Those statements do not foreclose our inquiry here. None of the cases sustained the use of libel laws to impose sanctions upon expression critical of the official conduct of public officials. The general proposition that freedom of expression upon public questions is secured by the First Amendment has long been settled by our decisions. Thus, we consider this case against the background of a profound national commitment to the principle that debate on public issues should be uninhibited, robust, and wide-open, and that it may well include vehement, caustic, and sometimes unpleasantly sharp attacks on government and public of-ficials. The present advertisement, as an expression of grievance and protest on one of the major public issues of our time, would seem clearly to qualify for the constitutional protection. The question is whether it forfeits that protection by the falsity of some of its factual statements and by its alleged defamation of respondent. Authorita-tive 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. Erroneous statement is inevitable in free debate, and it must be pro-tected if the freedoms of expression are to have the “breathing space” that they “need . . . to survive.” Injury to official reputation affords no more warrant for repressing speech that would otherwise be free than does factual error. Where judicial officers are involved, this Court has held that concern for the dignity and reputation of the courts does not justify the punishment as criminal contempt of criticism of the judge or his decision. This is true even though the utterance contains “half-truths” and “misinformation.” Such repression can be justified, if at all, only by a clear and present danger of the obstruction of justice. If judges are to be treated as “men of fortitude, able to thrive in a hardy climate,” surely the same must be true of other government officials, such as elected city commissioners. Criticism of their official conduct does not lose its constitutional protection merely because it is effective criticism, and hence diminishes their official reputations. If neither factual error nor defamatory content suffices to remove the constitutional shield from criticism of official conduct, the combination of the two elements is no less inadequate. This is the lesson to be drawn from the great controversy over the Sedition Act of 1798, which first crystallized a national awareness of the central meaning of the First Amendment. Although the Sedition Act was never tested in this Court, the attack upon its validity has carried the day in the court of history. Fines levied in its prosecution were repaid by Act of Congress on the ground that it was unconstitutional. Jefferson, as President, pardoned those who had been convicted and sentenced under the Act and remitted their fines.