Buried in an excellent article by Bradley A. Smith at The Volokh Conspiracy concerning the ill effects of the “government effort to regulate campaigns” is this bit of information that was news to me about the “I approved this message” tag at the end of political ads:
“The phrase is not actually required by federal law, but virtually every candidate chooses to say it. The reason is because a candidate who uses that phrase is legally entitled to the lowest unit rate for broadcast advertising; omission of the phrase leaves one to pay higher rates.”
The authors of the 2002 McCain-Feingold bill thought this little gem would prevent at least some of the negative ads which benefit challengers. Which is why campaign finance laws are inherently bogus—the lawmakers who write them will always attempt to create ways to protect themselves—the incumbents, and their special interests.