Here's how it works: The
FCC can't require shows to be checked with them beforehand, or make
rules like "You can't say '
shit' on the radio". That would be "
prior restraint of speech." What they can do is fine stations after they air something.
Howard Stern has been fined more than anyone else for stuff like this. As a result, he's forced to
censor himself and his callers, so the effect is the same. Of course, this has a "chilling effect" on free speech, but the Supreme Court said that because one cannot preview radio, and because it comes in unannounced and is broadcast in public, and because there is limited space in the radio spectrum (really!), some restrictions are allowed. Of course, where the FCC (which *did not* have in its charter anything about censorship) gets off making these rules, nobody knows.
Fortunately, internet radio makes all of this irrelevant - the
FCC can't control the net, because (according to
SCOTUS in
Reno v. ACLU) "the primary justification for intermediate scrutiny in th, the first supreme court case. e broadcast cases was spectrum scarcity. By contrast, the Internet has virtually limitless communications potential."