Describe at least one Supreme Court case that acted as a precedent and helped further define the First Amendment?

One significant Supreme Court case that defined the First Amendment is New York Times Co. v. Sullivan (1964). This landmark decision established the "actual malice" standard for press reports about public officials, protecting freedom of the press by requiring proof that a statement was made with knowledge of its falsity or with reckless disregard for the truth. This ruling reinforced the importance of robust debate and criticism in a democratic society, thus enhancing First Amendment protections for journalistic expression.