Wide World of Sex- In the latest twist in the broadening battle overdecency standards, the glam-metal band Mötley Crüe filed suit against NBC yesterday. The suit states that the network violated the group’s free-speech rights and weakened its sales by banning it after Vince Neil, the lead singer, used an expletive on the air in a Dec. 31 appearance on “The Tonight Show.”

The lawsuit, filed in a federal court in Los Angeles, accuses the network of censoring the band to mollify a Federal Communications Commission that has been increasingly quick to levy steep fines for broadcasting indecent material on television and radio. The lawsuit says the network, which banned the group after Mr. Neil inserted an expletive into his New Year’s greeting to Mötley Crüe’s drummer, Tommy Lee, added insult to injury by promoting a summer reality series featuring Mr. Lee.

The band, known for 1980’s hits like “Shout at the Devil” and “Girls, Girls, Girls,” is requesting a ruling that NBC’s ban is unconstitutional, a court order forcing the network to lift it, and unspecified financial damages tied to the band’s reduced media exposure.

“We meant no harm, but it feels that we’re being singled out unfairly,” said Nikki Sixx, the band’s bassist. “This is a discrimination issue, pure and simple. All we’ve ever asked is to be treated like everybody else, which is why we’re taking this action.” In a statement yesterday, NBC said: “To ensure compliance with its broadcast standards, NBC has the right to decide not to invite back guests who violate those standards and use an expletive during a live entertainment program. The lawsuit Mötley Crüe has filed against us is meritless.”

The band’s case appears somewhat quixotic, given that federal courts have afforded wide discretion to broadcasters to choose their own content. But it does illustrate the uneasiness of the relations between entertainers and the media companies that provide a platform for their fame in the cautious climate that has surrounded programmers since CBS’s Super Bowl fiasco last year, when Janet Jackson’s right breast was exposed during a half-time performance in front of tens of millions of viewers. Last year the F.C.C. proposed fines of nearly $8 million against broadcasters, primarily for risqué material, and executives have spoken openly of practicing self-censorship to avoid the agency’s crosshairs.

Jeff Zucker, president of NBC Universal Television Group, has provided examples of how the decency standards on broadcast television differ from those on cable. This past season, he played himself – albeit an expletive-spewing caricature of himself – in the limited-run Showtime series “Fat Actress.”

Whether performers can take legal action to influence programming is in serious doubt, however. Charles Tobin, a Washington lawyer who specializes in First Amendment law and has represented CNN and Fox, said: “The government has no right to censor people on the content of their speech. But time and again the Supreme Court has upheld the rights of broadcasters, newspapers and the other media to decide who it wants to give priority to. That includes the right to ban anyone they want to.”

“I think it’s a publicity stunt,” Mr. Tobin said of the Mötley Crüe suit. “It can’t get NBC’s help to boost its album through the airwaves. So it’s going to try and do it by dragging NBC into court.”

But the band’s lawyer, Skip Miller, argues that there are lower-court opinions supporting the notion that a private entity, like a television network, acting under government pressure, can be liable for damages for violating free-speech rights. Mr. Miller added that NBC’s action unfairly singled out Mötley Crüe because NBC had not announced similar bans on other performers who have uttered profanities on its airwaves, including the singer Bono of U2, or the singer John Mayer. (The F.C.C. found that NBC violated decency standards by broadcasting a vulgarity uttered by Bono during the Golden Globes in 2003, but did not impose a fine.)

“Once you’re on, and then you get banned,” Mr. Miller said, “the question is why? Is it because NBC decided to throw Mötley Crüe under the train? If it’s because of kowtowing to the F.C.C. and governmental pressure,” he continued, “yes, I do think that can be a First Amendment violation.”

In the lawsuit the band said Mr. Neil was not aware that his statement was being broadcast. But in any event, the band said, the live broadcast took place during late-night hours when federal prohibitions on indecent material have not traditionally been applied.Three weeks later, Mr. Zucker of NBC told a meeting of television critics that “Mötley Crüe will not be back on NBC.” He said that the New Year’s Eve edition of “The Tonight Show” would be broadcast on a five-second delay going forward.

As a result, the band said, a previously planned appearance on NBC’s “Last Call With Carson Daly” was called off. The band also said it was barred from appearing on other network programs, including “Late Night With Conan O’Brien,” and media exposure that cost it prospective ticket, merchandise and album sales, as well as corporate sponsorships. Even without appearances on the network, the band’s new double album, “Red, White & Crüe,” composed primarily of previously released songs, has sold a surprising 349,000 copies, according to Nielsen SoundScan.

Still, when the ban went into effect, just before the release of the album, it “was a tender, important time for them,” Mr. Miller said. “NBC’s action was overkill.”