The problem with this analysis is that it ignores the fact that the Harry Potter Lexicon Website quotes extensively from the books. In fact, the website contains almost the entire text of JK Rowlings book "Forgotten Beasts and Where to Find Them." Surely an author has the right to prevent a third party from republishing an entire book.

Furthermore, the publishers (RDR Books) have refused to provide a copy of the book to any of the copyright holders so it can be checked for infringing material. Under the circumstances I don't think JK Rowling and her lawyers had a choice.

Yes, everything depends on this factor: how much does the Lexicon quote from Rowling's other writings? A book dealing with a published work can quote rather extensively, if this serves the purpose of supporting the discussion and analysis which follow. A lexicon or dictionary which merely lists terms and defines them with quotations from the book(s) in question would likely be said to violate copyright, unless it was published with permission. However, after copyright expires, there would presumably be nothing to hinder such a publication.

The Harry Potter Lexicon does not define terms by quotes - they define, explain and discuss places, characters, spells,names etc etc with their own written entries, many of them essay length. Entires about the main characters includes discussion of character traits etc. They have created their own timelines from events in the books, and through this discovered inconsistencies and mistakes in the books. They have drawn their own maps of places by interpreting the description of them in the books etc. Whenever they are using actual quotes from the books, they are short and always credited.

I can't see that any of this constitutes copyright infringement. If the HP Lexicon loses this law suit, a lot of academic reference works will be endangered...