I'm not a lawyer, but...
I'm going to go out on a limb here, but I don't believe a phrase can be copyrighted. A logo containing a phrase can be trademarked. If you can prove authorship in a court of law, you can successfully sue for infringement. Recorded medium- be it music, movies, tv, books- provide an automatic copyright for people's works. Therefore, if I have a catchphrase on TV that I am heard to say often (say, 'you best get out of my business!'), I might be able to sue another individual who began using it on TV. However, there is no regulatory body. So if someone uses phrase coined on the show Seinfeld, someone involved in coming up with said phrase would have to sue to enforce the automatic copyright described earlier and prove that it's their intellectual property in a court of law.