The following is from the FCC web site...
OBSCENE AND INDECENT BROADCASTS
It is a violation of federal law to broadcast obscene or indecent programming. The prohibition is set forth at Title 18 United States Code, Section 1464 (18 U.S.C. § 1464). Congress has given the Federal Communications Commission the responsibility for administratively enforcing 18 U.S.C. § 1464. In doing so, the Commission may revoke a station license, issue a warning, or impose a monetary forfeiture for the broadcast of obscene or indecent material.
Obscene Broadcasts Prohibited at All Times
Obscene speech is not protected by the First Amendment and cannot be
broadcast at any time. To be obscene, material must meet a three-prong
Indecent Broadcasts Restricted
The Commission has defined broadcast indecency as language or material that, in context, depicts or describes, in terms patently offensive as measured by contemporary community standards for the broadcast medium, sexual or excretory organs or activities.
See Infinity Broadcasting Corporation of Pennsylvania, 2 FCC Rcd 2705
(1987). Indecent programming contains sexual or excretory references that
do not rise to the level of obscenity. As such, indecent material is protected by the First Amendment and cannot be banned entirely. It may, however, be restricted in order to avoid its broadcast during times of day when there is a reasonable risk that children may be in the audience. In the
wake of decisions rendered by the United States Court of Appeals for the
District of Columbia Circuit prior to 1995, the Commission concluded that
it must restrict its enforcement actions to indecent programming aired
during daytime hours, i.e., between the hours of 6:00 a.m. and 8:00
As a result, broadcasts -- both on television and radio -- that fit within the definition and that are aired between 6:00 a.m. and 10:00 p.m. are subject to indecency enforcement action.
The Commission does not independently monitor broadcasts for indecent material. Its enforcement actions are based on documented complaints of indecent or obscene broadcasting received from the public. Given the sensitive nature of these cases, it is important that the Commission be afforded as full a record as possible to evaluate allegations of obscene or indecent programming. Complaints should be directed to the FCC, Mass Media Bureau, Enforcement Division, Complaints and Political rogramming Branch, 1919 M Street, N.W., Washington, D.C. 20554, and should include: (1) a tape or transcript of the program or of significant excerpts; (2) the date and time of the broadcast; and (3) the call sign of the station involved. These tapes, of necessity, become part of the Commission's records and cannot be returned.