Yes, the Pope is coming to the US this week, but the real news is that Harry Potter author JK Rowling is also in the country and has just stepped into a New York City courtroom to testify in her lawsuit against a fan-created lexicon. The lawsuit has generated a wave of media coverage, though little of it is talking about what an important test of US fair use law the case could become.

Rowling will testify today after winning an injunction last November against Steve Vander Ark and his publisher. Vander Ark is the main author of the online Harry Potter Lexicon (currently featuring Google ads for "Gay Dumbledore T-shirts," a product that I was not previously aware existed), a site that Vander Ark has turned into a book. When the news was announcement, Rowling sued, claiming that a fan web site was one thing, but a complete paperback lexicon was another. Not only did she not want Vander Ark to profit from her work in this way, but Rowling made it clear that she had plans of her own to publish a lexicon.

"There is a big difference between the innumerable Harry Potter fan sites' latitude to discuss the Harry Potter Works in the context of free, ephemeral web sites and unilaterally repackaging those sites for sale in an effort to cash and monetarily on Ms. Rowling's creative works in contravention of her wishes and rights," says the federal complaint, filed last year in New York.

As we noted at the time, lexicons for popular series are common and both Narnia and Middle-Earth have multiple such guides. Although the works have generally been considered a "transformative" use of an author's work and world, Rowling is prepared to argue that the new lexicon does not, in fact, pass the fair use four-part test found in US copyright law.

If backed up by a judge, the case could place further limits on fair use and give authors more control over their plots, characters, and fake spells, long after the books are published.

In the books, Harry has a reputation as something of a rulebreaker and troublemaker at Hogwarts, but he's caused a fair bit of legal hufflepuff in the real world, too. Interest in the novels was so strong that unauthorized translations began popping up only days after the English version became available; while the official French translator needed months to get a translation out, a 16-year old did it in a few days... and was promptly picked up by the French police.

When the final book in the series came out, someone also went to the effort of photographing every page of a prerelease copy and posting the entire archive to the Internet (if the leaker really wanted to do us all a favor, he should have left off the epilogue and rewritten the ending, too). The leaker didn't manage to strip the camera's serial number from the EXIF metadata in the files, though, providing a potential means of identification. Scholastic doesn't appear to have gone after the snapper, who should next time pick up the digital equivalent of Harry's invisibility cloak before attempting to scoop the world.