He said yesterday it was a very difficult decision to give up the documents.
He would have broken the law for an informant who needed protecting, he said.
"I don't think it's worth going to the bitter end on it. If it was someone who really needed my protection, then I would.
"Obviously the Prime Minister doesn't.
"And we're talking about so little substance here that it will make very little difference to the court case."
Mr Ambrose recorded the now-infamous conversation between Mr Key and then-Act Party leader John Banks in an Auckland cafe during the 2011 election campaign, which became known as the teapot tapes.
The photographer is suing the Prime Minister for defamation over comments Mr Key made in the fallout over the recording.
After Roughan refused to release his documents, the case was referred to the Privacy Commissioner.
The commissioner's office told Roughan last week that it was bound by a previous judicial ruling by then-Chief High Court Judge Helen Winkelmann on Kim Dotcom's civil case against New Zealand's police and spying agencies.
Justice Winkelmann ruled that the privacy exemption for news media related specifically to "articles and programmes" and did not extend to books.
Her ruling was made after Herald journalist David Fisher refused to give up emails and interviews used to write the book The Secret Life of Dotcom.
Crown Law chose not to force Fisher to give up his recordings.
Media law expert Ursula Cheer, from the University of Canterbury, said yesterday that it was a surprise to many people when Justice Winkelmann interpreted the Privacy Act in such a literal way.
"It did look as though it would create problems and obviously it is. If this is happening with more journalists then they're going to be, in theory, chilled from writing books."
Dirty Politics author Nicky Hager successfully argued last year that his book was a "news activity".
Roughan attempted to use the same defence but the Privacy Commission said his book did not count as news gathering.
