Dan Brown in Court for The Da Vinci Code

Michael Baigent and Richard Leigh claim that Brown stole ideas presented in their book.

The two authors wrote in their books The Holy Blood and The Holy Grail, as early as 1982, that Jesus had a child, a hypothesis used by Brown in The Da Vinci Code.

A judge will start hearing opening arguments Monday.

The book The Da Vinci Code was published in 40 different countries, and has sold more than 30 million copies.

A movie based on the book, starring Tom Hanks and Audrey Tautou, will be coming out this year, and should be presented at the Cannes Film Festival.