Dan Brown believes authors should be free to draw from historical sources
Michael Baigent and Richard Leigh, who claimed that themes from The Holy Blood and the Holy Grail were plagiarised by Brown, now face a huge legal fees.
The High Court in London ruled in April 2006 that US writer Brown had not copied the work of the two authors.
The Da Vinci Code, published in 2003, has sold more than 40m copies.
Baigent and Leigh's book, which was published in 1982, has sold some two million copies and was a best-seller when it was first released. The co-authors said they were disappointed by the Appellate Court ruling.
"We believed, and still do, that non-fiction authors would suffer and be discouraged from extensive research if it was found that any author could take another's ideas, 'morph' and repackage them, then sell them on," they said.
Both books explore the idea that Jesus and Mary Magdalene had a child together, and their bloodline still exists... The movie was boring and a bigger disappointment than the court decision. Legal pub opens the matter up for discussion.