The following is from the Federal Communications Commission’s Manual for Broadcasters:

We sometimes receive complaints regarding the alleged use of subliminal techniques in radio and TV programming. Subliminal programming is designed to be perceived on a subconscious level only. Regardless of whether it is effective, the use of subliminal perception is inconsistent with a station’s obligation to serve the public interest because the broadcast is intended to be deceptive. (this is from the FCC manual for broadcasters)