The plaintiffs argued the book violates fair use by copying many passages of the book almost verbatim. "There is no word large enough flabbergasted, astonished. I believe that the book contains wholesale theft of 17 years of my hard work. It desecrates what I worked so hard to create," Hollywood Reporter quoted Rowling, as saying of the Lexicon book.
Lawyers for RDR publisher Roger Rapoport, the sole defendant in the case, argued that the author and publisher had put together a reference book equivalent to any other encyclopedia and that the "Potter" citations were covered under fair use.