The author spent a third day defending his work against a copyright infringement suit brought by Michael Baigent and Richard Leigh, authors of a 1982 nonfiction book, "The Holy Blood and the Holy Grail."
The suit is not against Brown, but his publisher, Random House, which also published "The Holy Blood and the Holy Grail." Random House denies the claims, and Brown says the assertion that he copied is "completely fanciful."
"I'm not crazy about the word 'copied,"' Brown testified. "Copying implies it is identical. It's not identical."
Brown said "The Holy Blood and the Holy Grail" was "one of the books in the mix" when he and his wife, Blythe Brown, were researching the novel.
He acknowledged "reworking" passages from the earlier book.
"That's how you incorporate research into a novel," Brown said.
Both books explore theories — dismissed by theologians — that Jesus married Mary Magdalene, the couple had a child and the bloodline survives. The lawyer for the plaintiffs, Jonathan Rayner James, spent the morning citing passages from "The Holy Blood and the Holy Grail" that he said had near equivalents in "The Da Vinci Code."
"I'm sorry, again, I have to disagree," said Brown, who appeared frustrated at the attorney's painstaking and sometimes repetitive questioning. "These are points of history that were available in a lot of other books we were using."
If Baigent and Leigh succeed in securing an injunction to bar the use of their material, they could hold up the scheduled May 19 film release of "The Da Vinci Code," starring Tom Hanks and Audrey Tautou.
Patrick Janson-Smith, who was involved with both books as former publisher of Transworld, a division of Random House, took the stand briefly to support his former employer.
In a witness statement, Janson-Smith said saw similarities between the two books, but no evidence of copying.
"'The Holy Blood and the Holy Grail' purports to be nonfiction; 'The Da Vinci Code' is a thriller," he said. "I thought the latter was a romping piece of good fiction. Like any thriller, no doubt it took ideas from any number of sources."
"The Da Vinci Code" has sold more than 40 million copies since its release three years ago, and has turned Brown, 41, into a literary superstar.
Brown testified Tuesday that he was certain he and his wife, who conducts much of his research, had read "The Holy Blood and the Holy Grail" only after he had submitted his synopsis for the novel that would become "The Da Vinci Code" to his agent in January
"I think it would be very unlikely that Blythe would be reading it without my knowledge," Brown said. "I'm very doubtful that she would buy it and I wouldn't know."
Brown has acknowledged that they read "The Holy Blood and the Holy Grail" while researching "The Da Vinci Code," but said they also used 38 other books and hundreds of documents, and that the British authors' book was not crucial to their work.
The third author of "The Holy Blood and the Holy Grail," Henry Lincoln, is not involved in the case. A lawyer for the plaintiffs, Paul Sutton, refused to say why he was not participating. Lincoln, who is in his 70s and reportedly in poor health, could not be reached for comment.
By Jill Lawless