United States defamation law

The origins of the United States' defamation laws pre-date the American Revolution; one influential case in 1734 involved John Peter Zenger and established precedent that "The Truth" is an absolute defense against charges of libel. (Previous English defamation law had not provided this guarantee.) Though the First Amendment of the U.S. Constitution was designed to protect freedom of the press, for most of the history of the United States, the U.S. Supreme Court failed to use it to rule on libel cases. This left libel laws, based upon the traditional "Common Law" of defamation inherited from the English legal system, mixed across the states. The 1964 case New York Times Co. v. Sullivan, however, radically changed the nature of libel law in the United States by establishing that public officials could win a suit for libel only when they could prove the media outlet in question knew either that the information was wholly and patently false or that it was published "with reckless disregard of whether it was false or not". Later Supreme Court cases barred strict liability for libel and forbid libel claims for statements that are so ridiculous as to be patently false. Recent cases have added precedent on defamation law and the Internet.

Defamation law in the United States is much less plaintiff-friendly than its counterparts in European and the Commonwealth countries due to the enforcement of the First Amendment. In the United States, a comprehensive discussion of what is and is not libel or slander is difficult, because the definition differs between different states, and under federal law. Some states codify what constitutes slander and libel together into the same set of laws. Criminal libel is rarely prosecuted but exists on the books in many states, and is constitutionally permitted in circumstances essentially identical to those where civil libels liability is constitutional. Defenses to libel that can result in dismissal before trial include the statement being one of opinion rather than fact or being "fair comment and criticism", though neither of these are imperatives on the US constitution. Truth is an absolute defense against defamation in the United States, meaning true statements cannot be defamatory.

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