I listen to a lot of Girl Talk. If you’re unfamiliar, he makes extensive mashups of old pop songs and hip-hop. Here’s a sample (and you’re welcome):
A typical album (which is more like one long “song”) contains many hundreds of samples, which would cost, like, a bazillion dollars to sample legally.
Girl Talk does not do what he does legally. Proudly so.
Yet the record industry doesn’t sue the bujeezus out of him. Why?
The Priceonomics blog has a theory: the record industry might lose the case and would rather not take that chance. The full article has some great history on copyright law, sampling, and hip-hop and is well worth a read.