Parody needs to mimic an original to make its point, and so has some claim to use the creation of its victim's, or collective victims', imagination, whereas satire--which has been defined as a work in which prevalent follies or vices are assailed with ridicule or are attacked through irony, derision, or wit--can stand on its own two feet and so requires justification for the very act of borrowing...
While we might not assign a high rank to the parodic element here, we think it fair to say that 2 Live Crew's song reasonably could be perceived as commenting on the original or criticizing it, to some degree. 2 Live Crew juxtaposes the romantic musings of a man whose fantasy comes true, with degrading taunts, a bawdy demand for sex, and a sigh of relief from paternal responsibility. The later words can be taken as a comment on the naivete of the original of an earlier day, as a rejection of its sentiment that ignores the ugliness of street life and the debasement that it signifies.
And I love that he quotes everyone from Nimmer to the OED to cases in the British Common court in the 1800s. Check out the textual range of the next quote:
We do not, of course, suggest that a parody may not harm the market at all, but when a lethal parody, like a scathing theater review, kills demand for the original, it does not produce a harm cognizable under the Copyright Act. Because "parody may quite legitimately aim at garroting the original, destroying it commercially as well as artistically," B. Kaplan, An Unhurried View of Copyright 69 (1967), the role of the courts is to distinguish between "biting criticism [that merely] suppresses demand [and] copyright infringement[, which] usurps it." Fisher v. Dees, 794 F.2d at 438.
This distinction between potentially remediable displacement and unremediable disparagement is reflected in the rule that there is no protectible derivative market for criticism. The market for potential derivative uses includes only those that creators of original works would in general develop or license others to develop. Yet the unlikelihood that creators of imaginative works will license critical reviews or lampoons of their own productions removes such uses from the very notion of a potential licensing market. "People ask . . . for criticism, but they only want praise." S. Maugham, Of Human Bondage 241 (Penguin ed. 1992).
But the case, and others like it, also does an astute job explaining copyright and its history, and can be a good primer for getting up to speed on the law, and with a historical grounding, which I think is particularly important.