By Jon Silverman
Legal affairs analyst
The plaintiffs' case was weak and vague, say lawyers
After the High Court ruled Da Vinci Code author Dan Brown did not breach the copyright of an earlier book, the BBC News website assesses the case's impact.
This judgement was expected.
Since there is no copyright in an idea, any claim for breach of copyright must rest on the way that the idea is expressed.
In this case, it was described as the "architecture" or "structure" of the work, The Holy Blood and the Holy Grail.
The plaintiffs claimed that this structure - the central theme - had been lifted by Dan Brown for the Da Vinci Code.
The judge rejected this claim even though he said that Brown had copied some language from the earlier book.
But to suggest, as Gail Rebuck, the chief executive of Random House, did outside court, that the judgement represented a significant victory for creative freedom, is probably going too far.
The judge himself acknowledged that nothing in the plaintiffs' case would have stultified creative endeavour or extended the boundaries of copyright protection.
In launching their claim, the authors of The Holy Blood and the Holy Grail, were aware of a similar High Court case brought in 1980 by an author called Ravenscroft, who wrote a non-fiction work titled The Spear of Destiny.
Co-incidentally, it also had Christ's fate as its central theme. Ravenscroft argued successfully that the novelist, James Herbert, had infringed his copyright by using the same characters, incidents and interpretation of events in parts of his thriller, The Spear.
But, as copyright lawyer, David Hooper, points out, the key issue is the amount of a book, both in quantity and quality, which is copied by someone else.
"Frankly, the only hope for the plaintiffs in the Da Vinci case would have been to produce a detailed schedule showing on which pages of Dan Brown's book their ideas, language and structure had been plagiarised.
"But their argument was vague and shifted course during the trial and was always based on a weak foundation."
Copyright lawyer Simon Gallant agrees. He was in court as an interested spectator when Michael Baigent was giving evidence.
"It was electrifying. I estimate that in a 20-minute period, he was forced to retract two or three claims and to apologise to Dan Brown for making them.
"I would have been astonished if he and his fellow plaintiff had won the case because the threshold you have to reach to prove infringement of copyright is a high one and they did not come close to it."
Under the Copyright, Designs and Patents Act 1988, the creators of literary, dramatic, musical and artistic works enjoy protection for original work if they can establish " a degree of labour, skill or judgement" in producing it.
That formula is crucial. The courts have denied protection to certain works, including some advertising slogans.
Once a work has been created, it will automatically be protected by copyright. No formal steps, such as registering it, need to be taken. Copyright in a literary work generally lasts for 70 years after the last remaining author of the work dies.