For six months, New Zealand's spies couldn't obtain high-level surveillance warrants because an "oversight" caused a gap in legislative powers.
The former Minister in charge of New Zealand's intelligence agencies said spies, not himself, would have copped the blame if a terrorist attack had occurred during the gap period.
The 'gap' between old and new legislation meant between 1 April 2017 and 28 September, the NZSIS couldn't issue visual surveillance warrants - a top secret high-grade rarely-used warrant.
Mr Finlayson said it was up to the intelligence agency - or the DPMC - to identify and flag the gap. He said "they would have been" to blame if a terrorist attack had occurred during the period.
When the NZSIS alerted then-Minister Finlayson to the legalisative gap in a June 2017 memo, his response was terse.
In a handwritten note on the documents, which were supplied to Newshub by the NZSIS, the minister wrote, "You will not be seeking a legislative solution AT ALL. Don't even bother asking. This should have been covered in the transitional provisions."
That's despite the NZSIS memo saying, "We are not seeking a legislative solution in the meantime."
A note of response from the Director-General of Security Rebecca Kitteridge says, "Discussed this comment with the Minister on 3 July and reiterated the fact that we are not seeking a change in legislation."
In further correspondence, Ms Kitteridge describes the gap as an "oversight... arising within the Cabinet recommendations and drafting instructions."
On Tuesday morning, Mr Finlayson said the back-and-forth was down to his determination to avoid using urgency to pass intelligence laws.
Mr Finlayson said he had taken on criticism of the Government's use of urgency to rush through intelligence legislation in previous years, and he sensed the memo was the precursor to a request to use urgency again.
"The media had criticised me and the Government in 2011 and 2013 when intelligence legislation was dealt with through urgency, and I was determined that while I was a minister there was going to be no repeat performance of that," he said.
He said any concerns should have been raised earlier, when he went through the legislation line by line with the agency.
"I had gone through the bill clause by clause with them very carefully, so in some respects it was a disciplinary matter on my part that I wasn't going to rush things through."
Ms Kitteridge told Newshub the gap was "by no means ideal".
But, she said, intelligence agencies "did have other tools in our toolbox".
Minister Responsible for the GCSB and NZSIS Andrew Little said ideally, when legislation changes, such powers are maintained, but he said the threat level created by the gap was minimal.
"The security and intelligence agencies have a number of means and mechanisms to keep tabs on people who are regarded as a risk. Visual surveillance is one of them.
"In the relatively short period of time they didn't have access to do that, they were able to cover their needs off through other means."