Copyright and free speech for authors: derivative works
The American Library Association filed an amicus curiae brief brief regarding the Salinger v. Colting case, in which J.D. Salinger is suing for infringement due to the use of concepts and characters from his Catcher in the Rye novel in the new novel 60 Years Later: Coming Through the Rye . Details of the case are provided by Anthony Falzone in his August 3, 2009 blog entry, "Confusion Over Copyright Injunctions and other Restraints of Speech". There are also many useful links in the post for further reading.
Seems there are new arguments for derivative works and transformative works that incorporate free speech rights and they are well worth following.