National repeatedly refused to answer question in Parliament yesterday about John Key's complaint to police about the so-called teapot tape, saying he had acted in his role as National Party leader, not Prime Minister.
And Labour challenged Mr Key's assertion that the freelance cameraman's actions in taping a cafe conversation between Mr Key and Act's John Banks had been "deemed unlawful", when it was only the opinion of a police officer, not a court.
"No such finding of wrong-doing has been made," Labour's David Parker told Parliament.
Police announced on Monday, while Mr Key was overseas, that they had decided not to prosecute cameraman Bradley Ambrose.
Ambrose left his microphone on a cafe table shared by Mr Key and Epsom Act candidate John Banks during an election campaign publicity stunt and taped the conversation inadvertently after being ordered out by Mr Key's staff.
Mr Key complained to the police and refused to give permission for the tape to be published.
Leader of the House Gerry Brownlee was delegated to answer questions from New Zealand First MP Denis O'Rourke on Mr Key's behalf but said there was no ministerial responsibility.
He claimed immunity on the grounds that the matter related to John Key as National Party leader, not his role as Prime Minister, and questions in Parliament can be directed only at members of the executive on their responsibilities as such, not as political leaders or Members of Parliament.
Labour's Trevor Mallard questioned how that was the case when Mr Key's response to the police dropping the case had been made by Mr Key as Prime Minister - he issued a press statement on Prime Ministerial letterhead.
Mr Brownlee said that as evidence that Mr Key had been acting as National Party leader, he had got his own private lawyer to act on the matter, not Crown Law.
Labour also pointed to a conversation between Barack Obama and Dmitry Medvedev at the conference in Seoul having been picked up by microphones and widely broadcast.
David Parker: "What was it about John Key's and John Bank's conversation in Epsom that made it more sensitive than a conversation between the Presidents of the United States and Russia?"
Mr O'Rourke, referring to the part of tape in which Mr Key reportedly says that New Zealand First's supporters were dying off, asked "has the Prime Minister sought or received any information on how many elderly New Zealand First supporters died during the course of the police investigation?"