Because of the pervasive nature of broadcasting, it has less First Amendment protection than other forms of communication. The F.C.C. was justified in concluding that Carlin's "Filthy Words" broadcast, though not obscene, was indecent, and subject to restriction.
In reference to this case, a poster in a WBAI broadcast booth warns radio broadcasters against using the seven dirty words.
In 1973 a father complained to the FCC that his son had heard the George Carlin routine "Filthy Words" broadcast one afternoon over WBAI, a Pacifica FoundationFM radio station in New York City. Pacifica received censure from the FCC, in the form of a letter of reprimand, for allegedly violating FCC regulations which prohibited broadcasting indecent material.
The U.S. Supreme Court upheld the FCC action in 1978, by a vote of 5 to 4, ruling that the routine was "indecent but not obscene". The Court accepted as compelling the government's interests in:
Shielding children from potentially offensive material, and
Ensuring that unwanted speech does not enter one's home.
The Court stated that the FCC had the authority to prohibit such broadcasts during hours when children were likely to be among the audience, and gave the FCC broad leeway to determine what constituted indecency in different contexts.
Tremblay, R. Wilfred (2003). "FCC v. Pacifica Foundation". In Parker, Richard A. (ed.). Free Speech on Trial: Communication Perspectives on Landmark Supreme Court Decisions. Tuscaloosa, AL: University of Alabama Press. pp. 218–233. ISBN0-8173-1301-X.