Whale Oil blogger Cameron Slater has launched court injunction proceedings in an attempt to prevent three of New Zealand's biggest media companies from publishing more of his hacked emails and Facebook conversations.
Mr Slater has served papers on APN New Zealand, Fairfax Media and MediaWorks to try to stop them quoting from emails and other communications allegedly taken from his accounts.
A fourth defendant listed as an ''unknown person'' is thought to be the individual behind the Whaledump Twitter account through which much of the hacked material has been released.
The blogger Slater also wants the news organisations to turn over to him the information they have.
The court action follows last month's publication of Nicky Hager book Dirty Politics book, based on Mr Slater's emails, which accused the National Party of attacking opponents through the Whaleoil blog.
The editor of New Zealand Herald titles, Tim Murphy, said he was surprised Mr Slater had waited so long given the book had been out several weeks.
The media companies will appear in court for an initial hearing at the High Court in Auckland this afternoon.
Media law expert Professor Ursula Cheer told Radio New Zealand's Morning Report programme the court will have to decide whether it is in the public's interest to know about the leaked emails.
Mr Slater would have to prove his emails were confidential and their publication would cause him harm, but there was also a strong argument that the information is in the public interest.
"If there's anything there that can be tied to the need for the public to have information in a functioning democracy - information about how MPs, leaders are behaving and so on - then that would still be seen as being in the public interest."