Which constitutional amendments did the Supreme Court rely on in New York Times Co. v. Sullivan?

In the landmark case New York Times Co. v. Sullivan (1964), the U.S. Supreme Court held that state libel laws must be limited to protect the freedom of speech and of the press. The Court relied on the First Amendment and the Fourteenth Amendment to establish that public officials cannot recover damages for defamatory falsehoods relating to their official conduct unless they prove "actual malice"—that the statement was made with knowledge of its falsity or with reckless disregard for the truth.1

By invoking these amendments, the Court constitutionalized the law of defamation, ensuring that public debate remains "uninhibited, robust, and wide-open". This ruling significantly broadened the protections afforded to the press against state-level libel claims.12