The US Supreme Court has agreed to review the issue of expletives on the airwaves, a move that may re-open the debate over broadcast indecency.
Bono's use of a swear word prompted the FCC crackdown
The court is to hear an appeal by the Federal Communications Commission.
The FCC's policy of fining networks for "fleeting expletives" or isolated utterances, is on hold following a legal challenge by Fox.
Analysts say the media environment has changed substantially since 1978 when the court last ruled on this issue.
The FCC toughened its stance on expletives after a 2003 broadcast by NBC of the Golden Globes award show when U2's lead singer Bono said that winning was "fucking brilliant".
The FCC concluded that the word had an inherent sexual connotation, its use violated rules governing decency and the broadcast of the expletive could have been avoided.
Pressure on US broadcasters also grew after pop star Janet Jackson briefly exposed her bare breast during a dance routine at the 2004 Super Bowl, prompting a flood of complaints.
Jackson's "wardrobe malfunction" has gone down in TV history
The case in question stems from a ruling by the FCC in March 2006 which found that the Fox television network had violated decency in its broadcasting of the Billboard Music Awards during which celebrities uttered profanities.
Fox, together with other networks ABC, NBC and CBS, brought legal challenges to the FCC's policy, arguing that the decency standard was unclear and undermined free speech protections.
An appeals court in New York ruled in favour of Fox, saying that the FCC had failed to explain adequately why it had changed its policy and that the policy itself was arbitrary and vague.
US Solicitor General Paul Clement, acting on behalf of the FCC and the Bush administration, argued that the ruling left the FCC "accountable for the coarsening of the airwaves while simultaneously denying it effective tools to address the problem".
The FCC, he said, had "hundreds of thousands" of complaints pending concerning the broadcast of expletives.
Broadcasters argue they do not aim to transmit swear words and should not face heavy fines for accidentally transmitting them.
The Supreme Court is expected to hear arguments in the autumn.
Separately, CBS is challenging a $550,000 (£246,000) fine for Janet Jackson's "wardrobe malfunction".
An appeals court in Philadelphia is to decide whether the incident was indecent or an accidental, fleeting glitch that does not warrant punishment, the Associated Press reports.
Broadcasters are barred from airing material considered indecent between 6am and 10pm, although the restrictions do not apply to cable or satellite services.