A court case in which two historians accuse US author Dan Brown of copying their work in his novel The Da Vinci Codeis due to finish tomorrow, ending one of the most closely watched copyright claims of recent years.
Michael Baigent and Richard Leigh wrote The Holy Blood and the Holy Grail, a work of historical conjecture published in 1982, which shares some of the same themes as Brown's best-selling religious thriller.
They are suing Brown's British publisher Random House, which also happens to be their own.
Both books raise the possibility that Jesus had a child by Mary Magdalene, she fled to France after the Crucifixion and Christ's bloodline survives to this day. They also associate Magdalene with the Holy Grail.
Authors warn that should the historians succeed, there would be serious implications for fiction writers who have always incorporated other people's ideas and research into their works.
Legal experts say the claimants face an uphill task to protect general ideas.
"You would hamper artistic creativity if you couldn't write a novel that theorises about a conspiracy theory," said Boston-based intellectual property lawyer Edward Naughton of Holland & Knight.
"That's why courts have been very wary about allowing protection of ideas that are this general."
In his summing up arguments on Friday, Random House's lawyer John Baldwin emphasised that ideas of a factual nature should be available for any reader to use.
"If it were otherwise the dissemination and discussion of history, science, religion and like topics would be stultified. Creativity of novelists, TV producers and film makers would be stymied," he said.
It could take weeks for Justice Peter Smith, who presided over three weeks of hearings, to deliver judgement.