The article is here; the Introduction and the Conclusion:
Sometimes lies are constitutionally punishable: Consider libel, false statements to government investigators, fraudulent charitable fundraising, and more. (I speak here of lies in the sense of knowing or reckless falsehoods, rather than honest mistakes.) But sometimes even deliberate lies are constitutionally protected. In New York Times v. Sullivan, the Court held that even deliberate lies (said with “actual malice”) about the government are constitutionally protected. And in United States v. Alvarez, five of the justices agreed that lies “about philosophy, religion, history, the social sciences, the arts, and the like” are generally protected.
The Supreme Court hasn’t explained where the line is drawn, and that leaves unclear where important areas of controversy—such as laws punishing lies in election campaigns—should fall. In this short article, I hope to offer an account that makes sense of the precedents and a framework for making future decisions….
The Court has never precisely explained when lies are constitutionally protected and when they are punishable. But the particular lines that it has drawn seem generally consistent with a comparative institutional approach to responding to lies. Government determination of which assertions are false and should therefore be punished is always perilous. When institutions—scholars, the government as speaker, the media, perhaps opposing election campaigns—there is a way to avoid the peril while still rebutting the lies. It’s imperfect, but it’s better than the alternative of government coercion; in such a situation, “the fitting remedy for” lies, as well as for “evil counsels,” is rebuttal.
But in other situations, when the harm from lies is serious and alternative institutions for rebutting the lies aren’t likely to exist, the government can indeed try to deter the lies by the threat of criminal prosecution or civil liability. That explains the constitutionality of properly limited libel law, and of the laws punishing fraud, perjury, and the like. And that can help decide where the lines can be drawn in the areas that remain unsettled.