Immigration Minister Iain Lees-Galloway is standing by his original decision to grant residency to Czech drug-smuggler Karel Sroubek, despite a review saying there were "powerful" reasons to deport him.
But Lees-Galloway concedes that the current process is too risky and plans to mitigate that by making ministerial intervention the option of last resort.
This is in line with recommendations from a review into Immigration NZ's processes, conducted by Mike Heron QC and released today.
The review was ordered in the wake of Lees-Galloway's controversial decision to grant Sroubek residency despite a conviction for drug-smuggling and an admission that he used a false identity to gain a resident visa.
Lees-Galloway revisited the case after it emerged that Sroubek may have travelled back to the Czech Republic, and eventually issued a new deportation notice to Sroubek.
Sroubek is appealing it from prison where he is serving his sentence for drug-smuggling
after being recently denied parole.
The Heron review found that the INZ processes were adequate but could be improved.
It said that Ministers applying absolute discretion may have limited time and did not usually receive free and frank advice on deportation cases - though Ministers were also free to take more time and seek further information.
"It is obvious to state that a process which allows a Minister to make a quick decision on a complex case with as little as an oral briefing and no advice is fraught with risk," the review said.
The risk could be mitigated if more decision-making was delegated to experienced experts, which would keep the Minister "above the fray".
Heron said it was also risky for the Minister to make a decision "without receiving any advice or recommendations and without any verification of the reliability of the information".
"This process puts both the Minister and INZ at risk. Whilst Sroubek is an unusual case, it does provide an example of the manifestation of that risk.
"The grounds contained in the case file summary were understood by most to be sufficiently powerful such that the original decision of the Minister was unexpected."
Speaking to reporters today, Lees-Galloway stood by his original decision to grant Sroubek residency.
"It [the Heron report] also says that in decisions of absolute discretion, unexpected decisions do happen."
He said his decision was appropriate given the existing process and the information available to him.
"The man is liable for deportation based on the second decision that I made, and that decision was made with additional information."
Lees-Galloway said he would implement Heron's recommendations, including allowing for free and frank advice to Ministers and for immigration officials to test the veracity of information provided to Ministers.
He said he had already changed the way he dealt with deportation cases, including allowing him more time to read the entire case file, and having a lawyer present to answer any legal questions.
Lees-Galloway was roundly criticised last year for not reading all of Sroubek's file and making his decision in less than an hour.
Today he would not say whether he should have read all of the file last year, saying only that he did that now for all complex cases.
Prime Minister Jacinda Ardern said she still had confidence in Lees-Galloway.
"These are complex cases and I think the Heron report rightly suggests the whole process needs to change, because both Immigration New Zealand and Ministers were carrying too much risk."