Kevin Martin, chairman of the FCC, said the agency was now considering whether to seek an appeal before all the judges of the appeals court or to take the matter directly to the Supreme Court. The decision, by a divided panel of the 2nd U.S. Circuit Court of Appeals in New York, was a sharp rebuke for the FCC and for the Bush administration. For the four television networks that filed the lawsuit, Fox, CBS, NBC and ABC, it was a major victory in a legal and cultural battle that they are waging with the commission and its supporters.

Under Bush, the FCC has expanded its indecency rules, taking a much harder line on obscenities uttered on broadcast television and radio.

While the court sent the case back to the commission to rewrite its indecency policy, it said that it was "doubtful" that the agency would be able to "adequately respond to the constitutional and statutory challenges raised by the networks."

The networks hailed the decision.

Martin, the chairman of the commission, attacked the court's reasoning.

He said that if the agency was unable to prohibit some vulgarities during prime time, "Hollywood will be able to say anything they want, whenever they want."

Beginning with the FCC's indecency finding in a case against NBC for an obscenity uttered by the U2 singer Bono during the Golden Globes awards ceremony in 2003, Bush's Republican and Democratic appointees to the commission have imposed a tougher policy by punishing any station that broadcasts a fleeting expletive.

That includes profanities blurted out on live shows like the Golden Globes or scripted shows like "NYPD Blue," which was cited in the case.

Reversing decades of more lenient policy, the commission had found that the mere utterance of certain profane words implied that sexual or excretory acts were carried out and therefore violated the indecency rules.

But the court said vulgar words were just as often used out of frustration or excitement, and not to convey any broader obscene meaning.

"In recent times even the top leaders of our government have used variants of these expletives in a manner that no reasonable person would believe referenced sexual or excretory organs or activities," the court said

Adopting an argument made by lawyers for NBC, the court then cited examples in which Bush and Cheney had used the same language that would be penalized under the policy. Bush was caught on videotape last July using a common vulgarity that the commission finds objectionable in a conversation with Prime Minister Tony Blair of Britain.

Three years ago, Cheney was widely reported to have muttered an angry profane version of "get lost" to Sen. Patrick Leahy on the floor of the U.S. Senate.