Prisons are big business in Australia and Dr Kath McFarlane Deputy Director of the Charles Sturt University (CSU) Centre for Law and Justice has commented on the economic arguments for and against private prisons in a recent interview with The Conversation Business Briefing.

The program questioned how well privatisation works, if prisons are better off, and if it's good value for money.

In the interview Dr McFarlane said, "Privatisation – we talk about it as if it's all or nothing, that you have a public jail or you have a public jail. It's really changed in the last 20 years, it's not like that anymore.

"You also have privatisation that's in different parts of the jail system. You have the privatisation of transport services, electronic monitoring, buy-ups – where prisoners can buy food and additional services. Those things are run by different companies.

"You don't have an argument that privatisation hasn't got a place, because it's here and it's been here for a long time. It's a really big shift to say, 'we're going to have a completely private jail'."

According to The Conversation, there are more than 41 000 daily full-time prisoners in Australia, according to the latest ABS data. Many of them are in private prisons - almost 20 per cent of the prison population according to a 2014 Productivity Commission report.

But we don't really know whether private prisons are more cost effective or produce better results. Private prison contracts are often 'commercial in confidence', and it's hard to know what exactly we've paid for. All this means we have to rely on watchdogs to ensure taxpayers are getting value for money, and it's tough for companies to really compete.

"Private operators have argued that they can do it cheaper, more efficiently and more humanely than the public system," Dr McFarlane said.

"The problem is that it's cheaper, but for what? It might be cheaper, and a huge criticism of private enterprises is that the cost savings come at the expense of the prison staff – less staff per prisoner to look after than you would have in a public prison. If you say you're going to do things cheaply, the first thing that is proven to go are the staff, and the second, is that it's at the sake of programs that could assist in having less prisoners."

The Conversation explains that prison job programs are often touted as a way to reduce prisoner recidivism, but again there is little evidence showing a positive impact. A study in the Northern Territory found that despite positive feedback from both prisoners and employers, these programs don't address other important factors affecting recidivism such as alcoholism and homelessness.