Writing for the Court, Justice William Brennan Jr. held that in order for a statement against a public official to be deemed defamatory, it must be proved that the statement was made with “actual malice.” Brennan argued that inherent in the right to free speech is protection from the criticism of government, and that this is especially true as applied to the press. He quoted President Madison, who said that “some degree of abuse is inseparable from the proper use of every thing; and in no instance is this more true than in that of the press.” The importance of the First Amendment, Brennan argues, is that it offers a robust protection of the rights to free speech and a free press.

Under common law, a statement is defamatory simply if it’s false and damages an individual’s reputation. Brennan warned that using the common law standard for defamation would have a chilling effect on speech critical of the government, writing that it “dampens the vigor and limits the variety of public debate” and that it’s “inconsistent with the First and Fourteenth Amendments.” Brennan feared that using this standard would lead to self-censorship over fears that they might face a libel lawsuit and be forced to pay expensive judgements.

In the case at hand, Brennan wrote that “[t]he 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.” In response to that question, Brennan wrote that an “erroneous statement is inevitable in free debate, and. . . must be protected if the freedoms of expression are to have the breathing space that they need. . . to survive.” Brennan concluded that a statement can only be considered defamatory is it is made with the knowledge that it was false or with reckless disregard as to its legitimacy. Ultimately, Brennan wrote that the First Amendment reflects “a profound national commitment to the principle that debate on public issues should be uninhibited, robust, and wide-open.”