When the entertainer Cher launched an expletive on live broadcast television in 2002, she probably had little idea she was triggering a major test of the government's ability to regulate content over the public airwaves.

On Tuesday, the Supreme Court will hear arguments in a case stemming from celebrities' use of isolated expletives as well as images of partial nudity during primetime broadcast programming. The case involves Cher's use of the F word on a Fox broadcast of the Billboard Music Awards and a similar outburst the following year on the same awards show by actress Nicole Richie.

The Court will also review an episode of ABC's "NYPD Blue" that featured a seven- second shot of an adult woman's nude buttocks. The Federal Communications Commission (FCC), charged with regulating public airwaves, found that the incidents violated its prohibitions against the broadcast of indecent material before 10 p.m.

At issue before the Court is whether the FCC's current indecency-enforcement policy violates the Constitution. A lower court struck it down, ruling it was "impermissibly vague." Fox Television; ABC, Inc.; and other broadcasters argue that the current policy is arbitrary and puts a chill on broadcast speech.

"The FCCs current enforcement policy, which subjects even isolated expletives or brief, scripted images to multi-million-dollar fines, cannot survive First Amendment scrutiny," argues Carter G. Philipps in court papers on behalf of Fox Television Stations INC.

The broadcasters are urging the Court to overturn a 34-year-old precedent in a case called FCC v. Pacifica Foundation. At issue in that case was a broadcast of comedian George Carlin's "filthy words" monologue, aired on a radio broadcast in the middle of the afternoon. After complaints from the public, the FCC ruled that the broadcast was indecent and could be subject to sanctions.

The Supreme Court rejected a First Amendment challenge to the FCC's determination, finding "of all forms of communication, broadcasting has the most limited First Amendment protection." The Court ruled narrowly, finding in part that the broadcast medium is unique because "material presented over the airwaves confronts the citizen, not only in public but in the privacy of the home." The Court also found that "broadcasting is uniquely accessible to children."

But the broadcasters currently argue that much has changed since Pacifica was decided and that they should no longer be regulated more restrictively than other media such as cable and the internet.

"Pacifica justified reduced First Amendment scrutiny of broadcast indecency regulation on the theory that broadcasting was uniquely pervasive and uniquely accessible to children," writes Seth P. Waxman, an attorney representing ABC, Inc. "Neither predicate is true today." Waxman points out that today the vast majority of households receive television through cable or satellite and are exposed to the internet.

"Over the past three decades," Phillips writes, "the media marketplace has changed dramatically, thoroughly undermining Pacifica's rational for its unequal treatment of broadcast speech under the First Amendment."

Although the broadcasters want the Court to overrule Pacifica, they say that even without doing so the Court can find that the FCC has improperly expanded its indecency policy since Pacifica in a way that is confusing and vague. They say, for example, the policy allows the use of expletives in a movie like "Saving Private Ryan" depicting war but found the same words indecent in "The Blues," a music documentary by Martin Scorsese.

"The Commission's vague standard has led to both arbitrary enforcement and a chill on protected expression," writes Waxman. "The Commission appears to base indecency determinations on its own artistic judgments, in derogation of fundamental constitutional principles. Broadcasters have refrained from engaging in constitutionally protected expression for fear of incurring multi-million dollar fines and license revocations."

After the particular episode of NYPD Blue aired in 2003, the FCC fined ABC and its affiliated stations a total of $1.24 million.

But Solicitor General Donald B. Verrilli Jr., arguing on behalf of the FCC, says in briefs that the FCC's enforcement rules remain a "reasonable and constitutional implementation of the government's compelling interest in protecting children from harmful exposure."

"Generations of parents," Verrilli writes, "have relied on indecency regulations to safeguard broadcast television as a relatively safe medium for their children. The rise of alternative communications media has strengthened, not undermined, that reliance interest."

He points out that when Cher swore during her acceptance speech, the broadcast was viewed by "millions of children including more than one million under age 11."

Professor Mark L. Rienzi of Catholic University, Columbus School of Law, says that even if the Court were to overrule Pacifica and say that broadcast networks have the same freedom from government regulation as cable, satellite or the internet, programming during prime time would not radically change. "At 8 o'clock at night most television stations decide that it is in their own best market interest to avoid constant uses of the F bomb and partial nudity," he says. "I would not expect the broadcasters to have wildly different programming if Pacifica is gone."

Although the broadcasters argue that parents have tools, like the V-Chip technology to block offensive programming, Verrilli says that those tools don't always work and that the FCC policy should be upheld. "So long as the federal government must exercise selectivity in allocating limited spectrum among numerous licensees (and broadcasters benefit from the use of a valuable public resource without charge), it may constitutionally require licenses to accept content-based restrictions that could not be imposed on other communications media."

Justice Sonia Sotomayor will not participate in this case because she dealt with it at the lower court level before her nomination to the Court.

The Court's ruling in this case is expected to affect another case, frozen in the lower court, regarding singer Janet Jackson's so-called "wardrobe malfunction" that exposed the entertainer's breast briefly during halftime of the Super Bowl in 2004.