It is rare for a copyright dispute to generate significant media attention, but this year seems to prove the exception to the rule. We have had Simon Fuller and Simon Cowell going head to head over a claim that Simon Cowell had infringed Simon Fuller's copyright in the programme format for Pop Idol by developing the X-Factor (that settled out of court) and now we have one of the best selling authors in the world being subjected to allegations of copyright infringement.

This latest dispute has generated media attention worldwide, given that its subject matter "The Da Vinci Code" is one of the best selling novels of all time. The facts are that two of the joint authors of "The Holy Blood and The Holy Grail" (HBHG) were suing the UK publishers of The Da Vinci Code, claiming copyright infringement. Interestingly they were suing Random House, the publishers of the Da Vinci Code (and also the publishers of HBHG). Anyone who publishes a work that infringes another's copyright is also guilty of infringement (secondary infringement but an offence nonetheless) and this was the basis of their case against Random House.

This claim for infringement of copyright centred largely on the claim that in writing the Da Vinci Code Dan Brown copied the central theme of HBHG (that Jesus was married and had a child with Mary Magdalene, that their descendants lived in France and founded the Merovingian Dynasty and that this secret has been protected by the Priory of Sion whose grand masters include Leonardo Da Vinci) and was therefore guilty of copyright infringement.

There is no doubt that Dan Brown did use this book as part of the research for his novel. In fact HBHG is referred to within the book. In addition, one of the key characters in the Da Vinci Code, Sir Leigh Teabing is a play on the names of the two authors who have raised this case, Richard Leigh and Michael Baigent. HBHG is, however, only one of a number of sources used by Dan Brown and his wife (who did a lot of the research).

The legal question being addressed was, is the copying of the theme sufficient to establish breach of copyright. It is a well worn phrase that there is no copyright in ideas, only in the expression of the ideas. Therefore it is in the expression of their ideas – the text of HBHG – that Leigh and Baigent have protection. Copyright reserves certain rights to the copyright owner and these include the right to make or authorise others to make copies of a work. Making a copy without permission constitutes copyright infringement. In order to assess if there has been copyright infringement the courts look at whether or not there has been "substantial" copying, i.e. it does not have to be an exact word for word copy, only that there are substantial similarities. This is assessed both in terms of quantity and quality.

The Court has recently found in favour of Brown, ruling that HBHG does not have a central theme, as was alleged by Leigh and Bagient, and that this had been an artificial creation for the purposes of the litigation. The Judge was clear that there was no copyright infringement, either by textual copying or non-textual copying, of a substantial part of HBHG.

The Judge was also keen to stress that this case was not about Dan Brown's skill and reputation as a thriller writer. This is very important as all fiction writers must do research and this case really centered on where the line between research ends and copying begins. A finding against Mr Brown would have had significant repercussions for research and would have significantly expanded what constitutes "substantial copying". Instead we are left with a clearer view of the ability of authors to research their work without infringing copyright.