Under the FDAMA a compound prescription must be 'unsolicited,' §353a(a), and the pharmacy, licensed pharmacist, or licensed physician compounding the drug may 'not advertise or promote the compounding of any particular drug, class of drug, or type of drug.' §353a(c). The pharmacy, licensed pharmacist, or licensed physician may, however, 'advertise and promote the compounding service.' Ps are a group of licensed pharmacies that specialize in drug compounding. They have prepared promotional materials that they distribute by mail and at medical conferences to inform patients and physicians of the use and effectiveness of specific compounded drugs. Ps sued D under a violation of the Free Speech Clause of the First Amendment. The District Court granted summary judgment to P, finding unconstitutional restrictions on commercial speech under Central Hudson. The Court severed the solicitation provisions from the rest of §503A of the FDAMA, 21 U. S. C. §353a, and left the Act's other compounding requirements intact. D appealed. The Court of Appeals agreed that the FDAMA's advertisement and solicitation restrictions fail Central Hudson's test for permissible regulation of commercial speech. D had not demonstrated that the speech restrictions would directly advance its interests or that alternatives less restrictive of speech were unavailable. The Court of Appeals disagreed, over severability. The Court of Appeals invalidated §503A in its entirety. The Supreme Court granted certiorari.