Labour Party MP Shane Jones is defending a decision he made in 2008 to approve citizenship for Chinese businessman Yan Yong Ming.
Mr Yan, also known as Yang Liu and Bill Liu, has been on trial for immigration fraud. An Auckland High Court judge will release his decision on the case later this week.
Mr Jones was the minister who overrode advice from officials and granted citizenship to the man he knew as Bill Liu in 2008.
On Tuesday morning he fronted up to caucus colleagues to give an account of his decision.
Outside caucus, the MP said he knew there were questions about the businessman's identity and that Interpol had raised a red flag.
However, on the weight of submissions made to him, he granted citizenship on humanitarian grounds.
Shane Jones said he made a very difficult call and will talk about it in more detail once there is a ruling in the court case.