In order to meet the specialized needs of particular patients, pharmacists may combine two or more drugs or alter the physical form of a drug through various processes referred to as compounding. The Food and Drug Administration and Modernization Act of 1997 prohibited pharmacies that compound prescription medication from advertising or promoting the compounding of any particular combination of drugs. The Act did not prohibit advertising the service of compounding drugs. Western States Medical Center (plaintiff) was one of a group of pharmacies that specialized in drug compounding services and advertised the effectiveness of certain drug combinations by mail and at medical conferences. The pharmacies filed suit in federal court to enjoin the enforcement of the advertising prohibitions as violative of First Amendment commercial free speech.