The Prime Minister is standing firm on his decision to keep John Banks as a minister, despite opposition calls for him to be stood down.
Police say there is insufficient evidence to charge Mr Banks in relation to allegations he falsely recorded donations to his 2010 Auckland mayoralty campaign as anonymous.
They say the file is now closed and they won't be investigating further.
John Key says Mr Banks told him he had acted within the law and has been proven correct by the police decision.
But the Labour Party says Mr Banks got off on a technicality and neither he, nor Mr Key, can claim he has been exonerated.
Both Labour and the Greens say Mr Banks hasn't acted ethically, but Mr Key disagrees.
He says the Cabinet manual is quite clear that the test of ethics relates to the time a minister held their warrant.
Mr Key says in his opinion, Mr Banks has been within the law and ethical and all the actions he has taken in the time he has been a minister.
He says the only consequence of the controversy may be a tightening of the law.
Mr Key says he will consider whether the local body law relating to donations should be made consistent with that governing general elections.
He says he thinks it might make sense to have the same rules applying to both types of election.