New Hampshire passed a law prohibiting 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” (Cato Institute Policy Analysis No. 295). New Hampshire also engages in gross viewpoint discrimination: it exempts insurers’ efforts to persuade doctors to use generic drugs, and runs an “academic detailing” program to discourage brand-name drug use. Remarkably, the First Circuit reversed a district court ruling that had invalidated the statute as unconstitutional, 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. Two companies that collect and sell health information and analysis filed a petition asking the Supreme Court to review the case. Cato, joining Washington Legal Foundation, Reason Foundation, and a group of current and former state officials, has filed a brief supporting that petition. Our brief argues that the Supreme Court should grant review because: 1) the speech at issue is worthy of First Amendment protection; 2) this case is a good vehicle for examining First Amendment issues attending state attempts to control health care costs (other states have passed similar laws); and 3) the lower court’s holding that a state may restrict speech to “level the playing field” conflicts with the Court’s precedent regarding both commercial speech and campaign finance regulation.