Safe Harbor Hours
Does your station want to broadcast some questionable material? Music that might have indecent language?
Well, now you don't need to tell that rap DJ with mad skills, "Nah, dude" — just schedule their show between 10:00pm and 6:00am.
But wait, how does this work? Read on for the rules from the FCC itself.
From the FCC website
Regarding the safe harbor period, Congress and the courts have instructed the Commission only to enforce the indecency standard between the hours of 6 a.m. and 10 p.m., local time. - when children are more likely to be in the audience. As a consequence, the Commission does not take action on indecent material aired between 10 p.m. and 6:00 a.m. In this way, constitutionally-protected free speech rights of adults are balanced with the need to protect children from harmful content.
More from Wikipedia
The term "safe harbor" refers to the hours during which broadcasters may transmit material deemed indecent for children. This "safe harbor", enforced by the Federal Communications Commission, extends—legally—from 10 PM to 6 AM and was established by the US Supreme Court case FCC v. Pacifica. This "safe harbor" is based on evidence that children 17 years of age and under are less likely to be in the audience during these hours. Sexual content and foul language are lawfully channeled to times of the day when children are less likely to be in the broadcast audience.
Example audio warning
Here is an example Safe Harbor audio announcement from XRAY.fm in Portland, OR:
"Between the hours of 10pm and 6am, KXRY may broadcast material that could be found offensive to some members of our audience. Listener discretion is advised."