More people are serving prison time for crimes of which they are later cleared, new data reveals.

Jack* spent nine months in jail and then two years on bail before a jury declared him not guilty of indecent assault.

He says he endured the mental anguish of prison while his family lost its sole earner and home.

"I feel like we've been violated in the most, most personal, deepest way possible," he says.

"It was a lot of 'what if's, 'what if's, and everyone would have that feeling, 'what if's. I don't have any money to pay big, significant lawyers to fight the charges or allegations. You do go to some dark places."

Jack's children were not allowed to see their dad for almost three years.

"When it was all over we sat down and had a big talk and it really, really took its toll on them. I believe had it gone any further it would've changed the direction of their lives."

Information released to RNZ reveals of the 13,879 remand prisoners who had their cases closed last year, 2138 or 15.4 per cent were not convicted of their most serious charge - about double the 2014 figure of 1075.

Criminal Bar Association vice president Sumudu Thode says it's more common than most people think.

"I think that is more than the general public would think in terms of innocent people being in prison," she says.

"There's the basic breaches of the New Zealand Bill of Rights Act - everybody is presumed innocent until proven otherwise, and these are innocent people because they're not proved to be guilty, at any point ... the charges were either dropped or withdrawn, or they were found not guilty at the end of a trial."

There's also an equity issue, because some people are only kept in prison because they didn't have an address for bail, Sumudu says.

At more than $150,000 to house each prisoner per year, she says it's a "waste of taxpayer money".

"If you think about over 2000 people being in custody, and some of these people may not have been in custody for a year, but if all of those people had spent at least 12 months, that's over $300 million spent on housing these people in prison, when they are innocent."

The total number of remand prisoners has increased and so has the amount of time they spend in custody - currently an average of 79 days, up from 56 days ten years ago (in 2013/14).

One person was on remand for almost six years (2084 days), before being released in 2023.

Justice Minister Paul Goldsmith says he's "very much concerned" about the increases and wants to speed up court processes.

However, he says keeping some accused people in prison has always been part of the justice system.

"There's a very high threshold before people are kept on remand because there's a concern around public safety, that doesn't always lead to a conviction. I suppose the best antidote to that is to ensure that we can speed up the processes of the courts so that fewer people are in that category."

Whether that threshold was in the right place was ultimately a matter for the judiciary to decide during each individual case, says Paul, while housing for those without a bail address was part of "a much broader challenge".

Earlier this year, the government announced a package aimed at supporting remanded inmates. For those yet to be convicted, it included optional reintegration programmes, alcohol and drug treatment, and educational or behavioural support.

Jack says that's a step in the right direction, but he also called for some acknowledgment of the time he had lost.

"Being found not guilty was a big relief, but there was nothing, not even a blinking 'sorry' ... no compensation, no anything. They just went on with their lives as if, 'oh well'," he says.

"We would like them to acknowledge their mistakes, and be held accountable."

*Real name withheld for privacy

-RNZ.