April 14 (Bloomberg) -- Billionaire author J.K. Rowling warned that plagiarists will flood the market with ``Harry Potter'' books unless a U.S. judge blocks publication of a dictionary of characters and creatures from her works.

Rowling, whose best-selling Potter books have sold more than 375 million copies worldwide, and Warner Bros. Entertainment sued Michigan-based RDR Books in October, seeking to block the release of the ``Harry Potter Lexicon'' because it infringes her work.

Her voice shaking in anger at times, Rowling, 42, told U.S. District Judge Robert Patterson in New York today that ``Lexicon'' author Steven Vander Ark copied large portions of her books ``wholesale,'' and that authors won't be able to protect their work if ``Lexicon'' is allowed to be published.

``Seventeen years of my work is being exploited here,'' Rowling testified. ``There is a massive principle at stake.''

In the ``Lexicon,'' Vander Ark listed the characters, places, spells, creatures and objects in the Potter books alphabetically and with minimal commentary. The key issue at the non-jury trial is whether Vander Ark, who runs a Potter-focused Web site of the same name as his book, made ``fair use'' of Rowling's work.

Federal law allows others to use copyrighted work for research, criticism and commentary, and the defense argued in court papers that their book falls within that meaning.

Praised Web Site

The Muskegon-based company, which is privately held, argued Rowling has praised the Harry Potter Web site that Vander Ark spent eight years running. Nearly 200 other such guides have been published, RDR said.

Rowling, whose testimony marked the first time she's appeared as a witness in a trial, said she intends to publish her own Harry Potter dictionary and give the proceeds to charity. The ``Lexicon'' would harm its sales, she said.

``Should it be published, I feel that carte blanche will be given to anybody who wants to make a quick bit of money,'' Rowling said.

Her seventh and final book about the fictional boy wizard, ``Harry Potter and the Deathly Hallows,'' broke publishing records by selling 8.3 million copies in the U.S. in its first 24 hours in July and 11.5 million copies in its first 10 days. In the U.S., the books are published by Scholastic Corp., which isn't involved in the case.

Five Films

Five films based on the books have grossed more than $4 billion, according to Warner Bros., a unit of New York-based Time Warner Inc., the world's largest media company.

RDR lawyers say Rowling is seeking a monopoly on the use of her characters, which may discourage publication of guides for other works. They noted that even Rowling once relied upon the A-to-Z organization of Vander Ark's Web site before making a public appearance.

``Reference books and commentaries should be able to be done by others than the author,'' RDR lawyer Lizbeth Hasse said in an interview. ``If a lexicon is not permitted for Harry Potter, it may not be permitted to other pieces of literature.''

Rowling spent three hours talking about the make-believe world of wizards she began creating 18 years ago. She explained how she derived the names of characters and objects she's invented and briefly discussed some themes that run through her books.

``Any guide to the Harry Potter books should have a lengthy entry on death,'' which the ``Lexicon'' lacks, she said. ``It is probably the major theme of the seven books.''

Remus Lupin

Rowling noted, for instance, that the character Remus Lupin, who was bitten by and became a werewolf, served as a metaphor for persons infected by HIV.

``There's not one single attempt to examine that,'' Rowling testified. ``All we have is abridged parts of my plot.''

Rowling said her intense focus on the court case has ``really decimated my creative work over the last month'' and interfered with her own writing. She said she wasn't certain she'd complete her encyclopedia should the market get flooded with others.

At the start of her testimony, Rowling appeared near tears as she recounted her struggle to get her first book published, going on public assistance at one point so she could feed her daughter.

``The characters mean so much to me,'' she said, adding of the series: ``It was my life, apart from my children.''

Fans and Scholars

Rowling said she's given fans and scholars wide latitude to comment on and critique her work, though not to repackage it and classify the end-result as scholarship. She said she hasn't interfered with thousands of Potter books published worldwide.

``What particularly galls is the lack of quotation marks,'' she testified. ``If Mr. Vander Ark had put quotations marks around everything he lifted, most of the `Lexicon' would be in quotation marks.''

On cross-examination, Rowling sparred with RDR lawyer David Hammer, who asked whether her lawyers had blocked publication of two other Potter encyclopedias. She acknowledged she previously praised Vander Ark's Web site, although she said today that it was largely because of his effort.

At times, Rowling corrected Hammer on the plot of her books, noting that Lord Voldemort, Harry Potter's nemesis, makes his initial appearance in her first book, not the second, as Hammer suggested.

Time Warner fell 10 cents to $14.17 in New York Stock Exchange composite trading.

The case is Warner Bros. Entertainment Inc. v. RDR Books, 07-cv-09667, U.S. District Court, Southern District of New York (Manhattan).

To contact the reporter on this story: David Glovin at the federal court in New York at dglovin@bloomberg.net.

Last Updated: April 14, 2008 17:53 EDT