In the U.S., the Supreme Court ruled in 1994 that the copywright owner's permission is not always required if the parody constitutes "fair use" of the original. The case involved the rap group 2 Live Crew recording a bawdy parody of Roy Orbison's "Oh, Pretty Woman" and being sued by Acuff-Rose Music for the same. The decision, as reported in the newspaper, said:

"Copyright law requires that permission be granted and royalties be paid when substantially rewriting a protected song, unless the new version represents a 'fair use' involving comment or criticism.

"The commercial nature of a work is only one factor in the decision of whether a parody is a fair use of a copyright work, he said. Judges also must consider how much of the original work was used in the copy and the potential that the parody might harm the market for the original, Souter wrote.

"It does not make a difference whether a parody is in good or bad taste, the justice wrote."

So for Americans it seems that, while royalties need to be paid for use of the melody, it's not a clearcut question as to whether permission is needed for the rewritten words.