Da Vinci Code Decision

In London, two goofy authors who claimed to be historians had sued Random House over the widely successful The Da Vinci Code by Dan Brown. They lost after a trial. See AP article here.

In 1982, Michael Baigent and Richard Leigh's book Holy Blood, Holy Grail was published. Their book supposedly chronicled the authors' historical research into the holy grail, ultimately speculating that Jesus was not cricified, but eventually married Mary Magdalene and had a family creating a bloodline: the holy grail. Again, this as supposedly historical research.

So these guys sue Random House alleging that The Da Vinci Code violated their copyright by "appropriat[ing] the architecture" and using the central theme of their 1982 work. They make no claim that Mr. Brown lifted unattributed passages from their book.

Wait a minute. Their 1982 book claims to be historical research. How can anyone claim to copyright history? Obviously, no one can. The suit was a tacit admission that the 1982 historical research was false, a mere fiction. The judge said as much in his decision, calling Baignet and Leigh "authors of pretend historical works."

Besides, ideas cannot be copyrighted. A copyright protects only the expressions of the idea.

Why did that case ever get as far as a trial?