The power of the Federal Communications Commission to punish a TV network for the antics of foul-mouthed celebrities at the Billboard Music Awards was pondered Wednesday by a skeptical panel of federal appeals judges.

Judges Rosemary Pooler, Pierre Leval and Peter Hall were on television themselves as they questioned an FCC lawyer on the agency’s decision to warn the Fox Broadcasting Company about expletives uttered by Cher and Nicole Richie — a warning that seemed to imply further offenses would be punished and one that media lawyers say signaled a dangerous change in FCC policy.