In broadcast law (particularly within U.S. law), the pervasiveness doctrine is the doctrine that because broadcast radio waves are available to anyone and therefore "uniquely pervasive", their content is subject to regulation. In general, profanity and sex, or other adult material deemed "indecent" by a broadcasting authority may not be broadcast outside of overnight "watershed" or "safe harbor" hours when children are unlikely to be awake. Material deemed "obscene" may still be prohibited at all times.