Lawyers for David and Victoria Beckham are seeking a High Court order against author Andrew Morton.
They want Mr Morton to disclose notebooks and audio tapes of interviews he used for his unauthorised biography Posh and Becks.
Last August, the couple settled their action against Mr Morton and his publishers by withdrawing their legal objections to the bulk of the book's contents.
But the Beckhams are still pursuing a breach of contract damages claim against their former bodyguard, Mark Niblett, who supplied Mr Morton with a large amount of material for his book.
For the purpose of that action, the couple are seeking the release of Mr Morton's records of his interviews with Mr Niblett.
The case is seen as a direct challenge to the traditional right of writers and journalists to protect their sources of information and their right to freedom of expression under the Human Rights Act.