WASHINGTON — The Supreme Court has ruled that the FCC can penalize broadcasters for airing as little as one single expletive over the air. The decision will not affect cable TV, satellite broadcasts or the Internet, none of which is transmitted over public airwaves.

In a 5-4 decision written by Justice Antonin Scalia, the court reversed a ruling by the 2nd U.S. Circuit Court of Appeals that said the FCC's decision to sanction "fleeting expletives" was arbitrary and capricious under federal law. That court decision had agreed with Fox Television stations, which broadcast the Billboard Music Awards, that such isolated utterances are not as potentially harmful to viewers as are other uses of sexual and excretory expressions long deemed "indecent" and banned by federal regulators.

"Even isolated utterances can be made in vulgar and shocking manner, and can constitute harmful first blows to children," Scalia wrote in the opinion.

Chief Justice John Roberts and Justices Anthony Kennedy, Clarence Thomas and Samuel Alito joined Scalia in the majority opinion.

Dissenting were liberal Justices John Paul Stevens, David Souter, Ruth Bader Ginsburg and Stephen Breyer. In a statement by Breyer, signed by the others, they said the FCC "failed adequately to explain why it changed its indecency policy from a policy permitting a single 'fleeting use' of an expletive, to a policy that made no such exception."

The court pointed out that broadcasters can go back to the federal appeals court in New York and argue that the FCC policy violates the 1st Amendment.

The dispute followed a series of uses of forbidden words by celebrities at live broadcasts of awards shows, including Cher at the 2002 Billboard Music Awards, televised on Fox, and Bono at the 2003 Golden Globes, televised on NBC. Bono's outburst led the FCC to reverse a longstanding policy that had punished only repeated expletives and declare that a single use of certain words could be sanctioned as indecent.

The new policy was developed under FCC Chairman Kevin Martin, a George W. Bush appointee who resigned in January. With the end of Commissioner Deborah Tate's term in early January, the commission currently has two vacant seats, waiting for President Obama to make new appointments.