The cameraman at the centre of the so-called Teapot Tapes controversy is suing the prime minister.
Bradley Ambrose was investigated by the police after he covered an event before the 2011 general election at which John Key met ACT leader John Banks.
The meeting, in a cafe in Newmarket, Auckland, for a cup of tea signalled to National voters that he endorsed Banks and ACT for the Epsom seat.
Ambrose left a tape recorder in a bag on their table and was unable to retrieve it.
Police decided not to prosecute Ambrose after he sent Key and Banks a letter of "regret".
Court lists today had Bradley Ambrose v John Key in the High Court for a case management telephone conference.
Key, speaking at a media standup in Hamilton, confirmed the action saying: "We've been aware for some time now that he's likely to file proceedings for defamation and we'll be defending that action."
He refused to be drawn further.
"It's a matter that's been before the court so we'll leave it there."
Ambrose's lawyers declined to comment.
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