Vermont passed a law prohibiting the exchange of a variety of socially important information. Most notably, the law outlaws the transfer of doctors’ prescription history to facilitate drug companies’ one-on-one marketing — a practice known as “detailing” — because it believes detailing drives up brand-name drug sales and, in turn, health care costs. The state knew that the First Amendment prevented it from banning detailing itself, so it made the practice more difficult indirectly. Yet data collection and transfer is protected speech — think academic research, or the phone book — and government efforts to regulate this type of speech also runs afoul of the First Amendment. See, e.g., Solveig Singleton, “Privacy as Censorship: A Skeptical View of Proposals to Regulate Privacy in the Private Sector”. The First Circuit had earlier upheld a similar New Hampshire law, somehow finding that the statute regulates conduct rather than speech and that, in any event, the judiciary should defer to the legislative branch’s judgment. When the Supreme Court declined to review that case (which cert petition Cato supported), Cato joined Pacific Legal Foundation, the Progress & Freedom Foundation, and two trade associations on a brief asking the Second Circuit to split with its First Circuit brethren and reject this dangerous narrowing of protection for free expression. Our brief argues that the Second Circuit should strike the Vermont law for three reasons: 1) the law regulates speech, not conduct, and thus is worthy of First Amendment protection; 2) the law abridges a range of expression that is not “commercial” speech — which, by Supreme Court precedent, is not fully protected; and 3) even if the law regulates “commercial” speech, that speech merits protection under the Court’s Central Hudson test.