Corrections admits it has opened itself up to the possibility of legal action as it may have broken the law by confining women to their cells for more than 23 hours a day.
On multiple occasions this year, inmates at the Auckland Region Women's Correctional Facility (ARWCF) in South Auckland have been denied the minimum one hour out of their cells each day required under the Corrections Act 2004.
In an interview with RNZ at the prison, chief custodial officer Neil Beales said Corrections did not have adequate records to check how many times this had occurred or whether it was justified on health or security grounds.
"There are times there where I just don't have the data available, or the depth and the detail of the data, to be sure that the ... law hasn't been breached."
Records were so poor that when RNZ first raised the issue with Corrections on April 29, prison managers had to review CCTV footage to check when the women had been out of their cells.
After reviewing footage for the four days between March 29 and April 1, for which no records had been kept, managers found that on 16 out of 30 occasions women were locked up for longer than 23 hours.
Beales acknowledged that the department could now be open to legal challenges, because he could not be sure whether the law had been broken.
"If somebody wanted to do that [take legal action], then that's entirely their prerogative to do that and we'd have to deal with that as it comes."
Beales said prison managers admitted mistakes had been made.
"They've owned that, they've acknowledged that there are certain things that weren't happening that should have been happening. I can tell you now that that's not happening right now at this site."
Beales said a new monitoring and recording system was in place and all women were now getting their minimum entitlements of at least an hour of exercise outside of their cells each day.
However, about 90 women in the high security unit were still confined to their cells for extended periods, getting just 90 minutes out of their cells each day for exercise.
Beales said in addition to the 90 minutes, some, but not all, of the women had additional time out for programmes, workshops and other activities.
"Some of them refuse to work, some of them can't work. So you've got gang issues, you can't unlock them with other people. There might be health issues or whatever. But when you unlock people, you've got to then have the staff to supervise them, and you've got to put them somewhere to do something and you don't always have that."
Under the United Nations' Nelson Mandela Rules, anything longer than 22 hours in a cell a day without meaningful human contact meets the definition of solitary confinement.
Beales said the long lockup hours were necessary.
"To have them wandering around the yards in each other's faces, becoming violent, hostile with each other, because there isn't anything else for them to do at that moment in time, is probably worse for them," he said. "If they're in a cell, they've got the TV, they've got their books. They're not sitting in a barren cell with nothing."
After reporting earlier this week on the findings of an internal review, which said ARWCF had a punitive culture, dysfunctional management and staff who were too quick to resort to force, RNZ was given a tour of the prison.
RNZ was shown areas of the prison where women were working - for between 20 and 60 cents an hour - packing goods and sewing face masks.
ARWCF, which has 371 inmates - 67 per cent of whom are Māori - also has a mothers unit, with two babies currently on site.
While Beales accepted the prison had failed to give some inmates their minimum entitlements to time outside their cells, he rejected the review's finding that the jail had a punitive culture.
"I don't agree with it. I've visited the site on many occasions. I have walked this site on many occasions. It's not what I see."
He said there had been an increase in the use of force at the prison over recent years but that was true of all prisons and gangs were a driving factor.
"I don't expect our staff to stand there and be attacked and get hurt as part of their job. If a member of staff is required to use force in order to keep themselves safe, they are trained to do that," he said.
"I don't see a culture of it here that would lend me to believe that there is an automatic use of force when there's a problem."