Original Post: Cartoons, Caricature and copyright

I would love to get into cartooning and caricature drawing but does anyone know if the same laws governing copyright apply here? ...."Dear Mr. President. Can I have your permission to make fun of you in a cartoon where it is really only your hair that is talking, a bit like that Doonesbury guy did with Dan Quayle a few years ago? Sincerely, Papa."...."Dear Papa. The black helicopter will be landing for you in a minute. very sincerely, D T"