The Justice Department, in this appeal, lumped both the expletives and nudity cases together, saying the court should decide the free speech questions as one.

Explicit language is heard with greater, albeit varying, frequency on cable television, the Internet, and satellite radio, which do not use public airwaves. But the federal government is charged with responding to viewer complaints of "indecent" language and images on broadcast television and radio, which is subject to greater regulation.

That is especially relevant during daytime and early evening hours, when larger numbers of families and younger viewers may be watching.

The commission formally reversed its policy in March 2004 to declare even a single use of an expletive could be illegal. In addition, a voluntary rating system is used by all television networks to warn viewers when material that might be offensive will be aired.

Much of the enforcement debate centered around the ABC television stations fined $27,500 each for airing the "NYPD Blue" episode featuring a woman with her breasts and buttocks exposed.

Another source of contention is whether broadcast radio and the TV networks -- ABC, CBS, Fox, NBC, and the CW -- should receive treatment differing from their satellite and cable cousins regarding content. Most broadcast stations are part of the basic cable packages people buy, and just 10% of the population receives its TV signals only through the airwaves. But the government countered that 69 million television sets are not connected to cable or satellite, and that broadcasting is the medium of choice for children.

The Supreme Court first ventured into the broadcast speech debate in 1978, when it ruled as indecent a monologue by comedian George Carlin on society's taboo surrounding "seven dirty words." The bit had received some radio airplay. The justices said "context" should be applied when deciding whether words or images are "indecent."

The major broadcast television networks say their scripted shows no longer air nudity, racy images or expletives, even after 10 p.m., when some potentially vulgar words are permitted.

Time Warner -- the parent company of CNN -- filed a supporting amicus brief in the high court dispute two years ago. The company is part owner of the CW broadcast network and operates several cable networks.

The case is FCC v. Fox Television Stations (10-1293).