Stop that bestselling author! He stole our Holy Blood!

So say Richard Leigh and Michael Baigent, co-authors of Holy Blood, Holy Grail, a 1982 book which proposed the historical theory that Mary Magdalene was the wife of Jesus Christ and the mother of his child (or children), and that early Christian sects and groups like the Knights Templar sought to preserve and protect this knowledge against the repressive tactics of the Catholic church. According to a lawsuit recently filed in London, they claim that Dan Brown, bestselling now-billionaire author of The Da Vinci Code, stole their ideas.

It's fairly obvious to anyone who's glanced at both books that Brown bases his plot on some of the same historical theories. One character, whose name is arguably an anagram of the two authors' names, explicitly mentions their book, commenting "the authors made some dubious leaps of faith in their analysis, but their fundamental premise is sound."

But did Brown actually copy anything under legal protection? The website of the British Patent Office clearly states, in its definition of copyright, that "copyright does not protect ideas. It protects the way the idea is expressed in a piece of work, but it does not protect the idea itself." A similar principle is asserted in US Copyright law.

If this is in fact the case, and if Leigh and Baigent cannot plausibly show that Brown actually lifted their prose rather than just using their historical theories as the basis for a fictional potboiler, then why hasn't this case been tossed out already? Do British courts lack a mechanism for dismissing cases with no legal or factual merit?

By way of analogy: if a historian were to write a nonfiction book proposing, or even proving, that Abraham Lincoln was gay, or that Richard III did or did not murder the two little princes in the Tower of London, or some other sensational historical theory, they would own a copyright over the actual words of the book in which they published that theory, but they would have no legal right to prohibit other historians from discussing that theory or the facts that they cited to support it. Nor would they have a legal right to prevent novelists from writing potboiling fictional treatments featuring Gay Abe or Bloody Richard or Good King Dick, respectively. Historical facts and personages are not copyrightable.

Furthermore, it seems unlikely that L. & B. could show economic harm even if Brown had infringed on their work. If anything, the Da Vinci frenzy has boosted the sales of their somewhat turgidly written book.

A further curiosity: both authors' books are published by Random House.

So. Is this a real lawsuit, or just a Barnumesque publicity stunt? And if it's a real lawsuit, why hasn't it been dismissed as frivolous?

And why haven't the two suing authors figured out that, if anything, Brown has done them a favor by launching their eccentric theory into the center of public consciousness? They could make a fortune just by going on a lecturing tour, or making a video documentary version of Holy Blood Holy Grail.

That, I suppose, would make too much sense.