Google is being taken to court by the Association of American Publishers for its Google Book Search project.

Publishers and authors are concerned that the project does not adhere to current copyright law, which mandates that permission must be asked of copyright holders before publishing works. Google has taken the line that authors and publishers may “opt out” of having their works included in the project, rather than that they must “opt in”.

The Google Book Search project is digitising and making available online the libraries of four US universities, as well as Oxford University library and the New York Public Library.

Microsoft and Yahoo are also involved in a book scanning project, and have been subpoened by Google, who is anxious to know more about what copyright permissions they have received. The two companies are backing a project called the Open Content Alliance or OCA, which is also supported by Adobe, the UK’s National Archives, the Smithsonian Institute, and HP.

The big difference between the OCA and Google Book Search is that the OCA seeks permission before copying or digitising a work.

Google’s subpoenas will give the company’s legal advisors access to the copyright status of books already scanned by rival projects. However a judge in the case has ruled that any information given out by Yahoo and Microsoft because of the subpoenas will be kept confidential.