Harry Potter creator J.K. Rowling will take to the witness stand next month in her legal bid to stop the planned publication of an unofficial encyclopedia.

The author and Warner Brothers, which owns the rights to the boy wizard novels, filed a lawsuit against publisher RDR Books in October (07) over The Harry Potter Lexicon, based on fan Steve Vander Ark’s website of the same name. The book was due for publication in November last year (07).

On Monday, a New York Federal District Court Judge ordered the case to go to trial on April 14. A lawyer for RDR Books confirmed Rowling was expected to appear to give evidence in the case.

Rowling herself insists she plans to write her own definitive Harry Potter encyclopedia - including previously unseen material - and will donate the proceeds to charity.