How to write a parody, legally speaking:
Suntrust v Houghton Mifflin, 252 F. 3d 1165 (11th Cir. 2001)

How NOT to write a parody, legally speaking:
Salinger v. Colting, 641 F. Supp. 2d 250 (S.D.N.Y. July 1, 2009)

[Excerped from the chapter, About The Book]

Many people who knew of my intent to create this parody were concerned about its legal aspects, because given the... uh... let us say "legendary intransigence" of your average Objectivist, the odds of receiving official permission to pen a critical parody of the greatest novel ever written would appear to be precisely zero.  Fortunately, the legal minefield had already been cleared by a woman having an interesting coincidence of name, one Alice Randall.  In 2001, Ms. Randall released a parody of Martha Mitchell's epic tale, Gone With The Wind, cleverly titled, The Wind Done Gone, which tells the exact same story during the exact same time frame, even including many of the novel's passages--except the story is told from the slaves' point of view.  (I toyed with the idea of naming this tome Atlas Done Shrugged, but concluded that the title was insufficiently on topic.)  As you would expect, the Margaret Mitchell estate took frenzied exception to the apparent infringement, but after a protracted legal battle (ending with Suntrust v. Houghton Mifflin) the courts ruled that the parody was permissible without permission, as is this one, and the thousands of other creative works of critical fan fiction that have proliferated in Ms. Randall's wake.  The literary world is a richer place for her courage.