The justices avoided a broad ruling on the First Amendment and whether traditional broadcasters now deserve the same free-speech rights as cable TV and other media.

WASHINGTON — The Supreme Court, in a narrow ruling Thursday, rejected fines levied against several television networks for having aired “fleeting expletives” or momentary nudity nearly a decade ago.

The justices said the broadcasters were not given “fair notice” the lapses would be treated as major violations of the federal broadcast rules against indecency.

The justices avoided a broad ruling on the First Amendment and whether traditional broadcasters now deserve the same free-speech rights as cable TV and other media.

They may have been closely divided on that fundamental question and opted to resolve the pending cases without making a major change in the law. Justice Sonia Sotomayor sat out the case because she had considered the same matter when on the U.S. Court of Appeals in New York. Her absence created the prospect of a 4-4 split.

Thursday’s decision in Federal Communications Commission (FCC) v. Fox Television leaves uncertain the status of the current rules on indecency.

Since the 1930s, it has been illegal for radio and television broadcasters who use the public airwaves to transmit “any obscene (or) indecent” words or images. In 1978, the court agreed with the FCC that comedian George Carlin’s “seven dirty words” monologue was indecent for broadcast at midday on the radio.

About a decade ago, the FCC decided to take a stronger stand against occasional four-letter words and displays of nudity on prime-time broadcasts. In 2004, the commission decided Fox, ABC and NBC had violated this new policy. Fox and NBC had broadcast award shows in which celebrities, including Cher and Bono, had used obscenities. ABC was held to have violated the policy by airing a seven-second scene showing partial nudity on an episode of “NYPD Blue.”

The broadcasters went to court in New York, arguing that the fines were unfair and unconstitutional. They have won a series of rulings there but no final victory.

Three years ago, the high court ruled the FCC had the authority to adopt a new and stricter policy on indecency.

When the case went back to New York, the federal appeals court ruled again for the broadcasters.

The case came back to the high court in January.

The court ruled Thursday only that the fines levied on Fox, ABC and NBC were unfair because their objectionable broadcasts happened before the FCC had adopted its strict policy against fleeting expletives.

“A fundamental principle in our legal system is that laws which regulate persons or entities must give fair notice of conduct that is forbidden or required,” said Justice Anthony Kennedy, writing for a unanimous court. “The commission failed to give Fox or ABC fair notice … “

Also Thursday:

Drug ruling: In a 5-4 decision, the court said the Fair Sentencing Act, which relaxed mandatory prison sentences for crack-cocaine offenses, covers people who were charged but not yet sentenced when the act became law in 2010. The ruling resolved a dispute in favor of Corey Hill and Edward Dorsey, who were arrested in 2007 and 2008 for selling crack and faced mandatory 10-year sentences in Illinois. But they weren’t sentenced until after the Fair Sentencing Act went into effect in August 2010. Hill would have been sentenced to about four years under the new law; Dorsey would not have faced a minimum sentence.

Union decision: In a 7-2 decision, justices ruled that unions must win approval in advance from dissenting members before they collect extra dues midyear to pay for a political campaign. The justices said in ruling on the dispute out of California that the Service Employees International Union violated the First Amendment when it collected an extra $6.45 a month from state employees in fall 2005. Union leaders had vowed to create a $12 million fund to oppose two ballot measures sponsored by then-Gov. Arnold Schwarzenegger seen as targeting public unions. They decided on a midyear dues increase to pay for the campaign.

Material from The Associated Press is included in this report.