A former inmate and drug addict has backed the findings of a new report by the Government science advisor, which slams the New Zealand prison system as expensive and at times ineffective.
The report - released by the Office of the Prime Minister's chief science advisor, Professor Sir Peter Gluckman - concluded prisons are "extremely expensive training grounds for further offending".
It also calls them "recruitment centres for gangs".
The number of inmates has almost doubled in the last 20 years, and our prisons are now bulging at the seams.
Mitch Ingram spent time in Mount Eden Remand and two other jails after selling methamphetamine in cities from Auckland to Invercargill.
"To fund my addiction I had to sell drugs, and I ended up getting arrested for supply of methamphetamine and cannabis - and ended up getting sentenced to three-and-a-half years in jail."
It's the jails this report says have become a training ground for criminals.
It states: "Prison teaches young offenders the skills of the meth trade; it does not resource them to make different choices".
Ingram says he was offered cannabis on his first day inside, and that drugs were easier to get behind bars than on the street.
"It's far easier on the inside because you don't have to travel as far," he says. "You just say what you want and they'll come to you and you're in the same unit."
But the former addict didn't succumb to temptation. He stayed clean, and puts that down to the rehab he did before going inside.
"I spent 11 months in treatment before going into jail. I arrived in jail clean, free from the want to use."
It's treatment and rehabilitation that the report says we must invest more in.
Johnny Dow, head of drug treatment centre Higher Ground, says there's a four-month waiting list to get a room.
"The war on drugs is not working. You need to look at it as a health issue - and that's exactly what it is," he explained.
On average, Mr Dow says it costs $100,000 to keep one inmate locked up for one year.
"For that amount of money we could put about four people through treatment a year."
But National's Justice Spokesperson Mark Mitchell doesn't think prisons are a waste of money.
"There is a cost associated with keeping people in jail, but they are in jail for a reason - and that is to make sure that actually the community is kept safe."
But it's exactly that type of political statement which the report's authors suggest is problematic.
It says the political decisions of previous governments wanting to appear tough on crime are the reason prisons are filling up and people are staying on parole longer.
If other inmates have stories they want to share, contact Michael Morrah at email@example.com.