Fair Use Doctrine and Libel Law?

Fair use is essential to a democratic media. It successfully allows for parodies and other forms of satire for copyrighted works. These types of commentaries on the originals should be upheld as a form of free expression. Without them, we would be facing even more instances of conglomerates and other cases where a multitude of works were owned by a handful of corporations. These would then become forever locked away... never to be heard or seen again. The beneficial thing about parodies is that it generates interest in the original. Trust me, someone is waiting out there for a satire on Mork and Mindy, so that they can re-launch the original back into circulation and benefit off the publicity. It's a classic pattern of development. Take South Park's, "The Passion of the Jew" - which was a clear parody of Passion of the Christ, a famous Mel Gibson production. Not only was the South Park version wildly popular among it's cult following, but it led some of those viewers to watch the Passion of the Christ to fully understand the South Park parody. Genius! Both parties profited.

Now in regards to libel? Well the relationship of Fair Use to libel is loose at best. Is there even a landmark case here? I could see it being an issue in copyright law but not in libel cases. Someone wasn't paying attention in mass comm law if they think that these two principles are closely related to each other. Show me a case and prove me wrong.

Getting to the issue - libel is libel and the only real defense in a libel case is the truth.