Parodies cannot be prevented or forbidden. And they're one of the strongest forces in folk music.

When Weird Al Yankovic has a big hit with his own new words to a popular melody, mechanical royalties are paid to the composer(s) of the tune -- and they make money. They composers cannot prevent the parody from being recorded, but they can sue if they don't receive their royalty payment.

Nobody's melody is safe from the parodist -- not even Irving Berlin. In 1961, a group of music publishers representing songwriters (including Berlin, Cole Porter and Richard Rogers) filed a $25 million lawsuit (and that was a lot of money 50 years ago) against Mad Magazine for copyright infringement following the publication of a nifty book called "Sing Along With Mad:" a collection of parody lyrics "sung to the tune of" many popular standards. The plaintiffs hoped to establish a legal precedent that only a song's composers had the legal right to parody that song.

The U.S. District Court ruled largely in favor of Mad Magazine in 1963, upholding its right to print 23 of the 25 song parodies under dispute. An exception was found in the cases of two parodies, "Always" (sung to the tune of "Always") and "There's No Business Like No Business" (sung to the tune of "There's No Business Like Show Business"). Relying on the same subject nouns ("always" and "business"), these were found to be overly similar to the originals. The music publishers appealed the ruling, but the U.S. Court of Appeals not only upheld the pro-Mad decision in regard to the 23 songs, it stripped the publishers of their limited victory regarding the remaining two songs. The publishers again appealed, but the Supreme Court refused to hear it, thus allowing the decision to stand.

The two songs that were excluded because they failed to make what lawyers call "material changes" to the original lyric content. If you don't make a significant "material changes" to the original lyric, the composer may exercise their prerogative to make you sing it exactly the way they wrote it (because you didn't make enough "material changes" to constitute a parody.

For example, I was once sued in federal court for having recorded someone else's composition, and in doing so had changed just a couple of words and made a verse into a chorus.