WASHINGTON — The Supreme Court unanimously threw out fines and sanctions today against broadcasters who violated the Federal Communications Commission policy regulating curse words and nudity on broadcast television.

But the justices declined to issue a broad ruling on the constitutionality of the FCC indecency policy. Instead, the court concluded only that broadcasters could not have known in advance that obscenities uttered during awards show programs and a brief display of nudity on an episode of ABC’s NYPD Blue could give rise to sanctions. ABC and 45 affiliates were hit with proposed fines totaling nearly $1.24 million.

The justices said the FCC is free to revise its indecency policy.

It was the second time the court has confronted, but not ruled conclusively on, the FCC’s policy on isolated expletives. Justice Anthony Kennedy said in his opinion for the court that “it is unnecessary for the court to address the constitutionality of the current policy.”

The case arose from a change in the FCC’s long-standing policy on curse words. For many years, the agency did not take action against broadcasters for one-time uses of curse words. But, following several awards shows with cursing celebrities in 2002 and 2003, the FCC toughened its policy after it concluded that a one-free-expletive rule did not make sense in the context of keeping the air waves free of indecency when children are likely to be watching television.

But Kennedy said the commission did not adequately explain that under the new policy “a fleeting expletive or a brief shot of nudity could be actionably indecent.”

The stepped-up indecency enforcement, including issuing record fines for violations, also was spurred in part by widespread public outrage following Janet Jackson’s breast-baring performance during the 2004 Super Bowl halftime show.

That incident, and the FCC’s proposed fine of $550,000, are not part of the current case. The government has an appeal pending of a lower court ruling that threw out the fine in that case.

The material at issue in today’s decision includes the isolated use of expletives as well as fines against broadcasters who showed a woman’s nude buttocks on a 2003 episode of the show “NYPD Blue.”

In December 2002, singer Cher used the phrase “F— ’em” during the Billboard Music Awards show on the Fox television network. A month later, U2 lead singer Bono uttered the phrase “f—— brilliant” during NBC’s broadcast of the Golden Globes awards show. In the December 2003 Billboard awards show on Fox, reality show star Nicole Richie said, “Have you ever tried to get cow s— out of a Prada purse? It’s not so f——simple.”

But the challenge went beyond just the penalties for the use of fleeting expletives. The broadcasters wanted the court to free them from all regulation of content around the clock. The court’s 1978 Pacifica decision upheld the FCC’s reprimand of a New York radio station for airing a George Carlin monologue containing a 12-minute string of expletives in the middle of the afternoon.

The broadcasters argued that the revolution in technology that has brought the Internet, satellite television and cable makes even the old rules obsolete. The regulations only apply to broadcast channels.

Viewers have so many options, unlike the handful of channels they had available in the 1960s and 1970s, when the court last weighed in on indecency on the airwaves. And in many cases, viewers don’t even know when they are switching between the older broadcast channels and cable.

Still, the regulated broadcast channels provide what the government has called a safe haven of milder programming. And those channels remain dominant, even in the Internet age, the administration said.

Justice Ruth Bader Ginsburg said in a brief opinion that she would have overturned the Pacifica ruling, which she called wrong even when it was decided. Justice Sonia Sotomayor did not take part in the case because she was involved in an earlier version while sitting as an appeals court judge in New York.