U.S. District Judge George B. Daniels said Dan Brown's book exploring codes hidden in Leonardo Da Vinci's artwork is not substantially similar to "Daughter of God," by Lewis Perdue.
Brown's book "is simply a different story," Daniels said.
"Although both novels at issue are mystery thrillers, 'Daughter of God' is more action-packed, with several gunfights and violent deaths," Daniels said in a ruling dated Thursday. "'The Da Vinci Code,' on the other hand, is an intellectual, complex treasure hunt, focusing more on the codes, number sequences, cryptexes and hidden messages left behind as clues than on any physical adventure."
He also ruled out any copyright violations of Perdue's 1983 novel "The Da Vinci Legacy."
Brown and publisher Random House Inc. last year asked the court for a declaratory judgment that Brown's 2003 novel does not infringe on Perdue's work after Perdue threatened to sue.
In a countersuit, Perdue asked the judge to rule there was infringement and award him $150 million in damages.
Perdue alleged that Brown copied the basic premise of "Daughter of God," including notions that history is controlled by victors, not losers, and the importance of the Roman Emperor Constantine in requiring a transition from a female to a male dominated religion.
"Ideas and general literary themes themselves are unprotectible under the copyright law," the judge said.
Perdue lawyer Bruce Lederman declined to comment.
Elizabeth McNamara, a lawyer for Brown, said she and her client were pleased with the decision.