A Harry Potter fan creates a “Lexicon” (a type of encyclopedia or companion book) for the famous literary series by J.K. Rowling.  Is such a work a “transformative” new work, and therefore a “fair use” of the copyrighted series, or is it a “derivative” work, and therefore under the exclusive control of the copyright owner?  In the case of the Harry Potter Lexicon, a District Court in New York ruled that the work contained too much copying and not enough transformation to be a “fair use” of Rowling’s books.  An appeal is pending.  A comprehensive look at the Court’s opinion can be found here:

http://www.groklaw.net/article.php?story=20080909014304275

–Matt