The company had an inauspicious beginning at Mt Eden, totting up $300,000 in fines for not keeping a lid on assaults and wrongly releasing and detaining inmates. It has since improved, Corrections says, placing it in one of the "top three" prisons in the country in the latest measurements.
The Corrections union now says Serco seriously under-staffs Mt Eden Prison, leading to violence for wardens and a high churn of new recruits. It's a charge the company denies, and not for the first time.
The same charges swirled around Serco's infamous Christmas Island detention centre, where under-staffing was blamed for inmate violence and self-harm. (Serco countered that detainees created a culture of self-harm and used the practice as a "bargaining tool").
There's no doubt Serco buys itself a boatload of trouble by taking on such high-profile contracts as the Australian detention centres because there is money to be made - and what amazing money it is. Four years ago, says the Sydney Morning Herald, the company had contracts with the Australian Government of A$353 million; this year it will be paid A$1.86 billion for its services.
Last year its revenue got a fillip from the rising number of boat people - "irregular maritime arrivals", Serco calls them. Serco has yet to make a dividend from New Zealand, but there is no reason to doubt that it has done the numbers and sees plenty of scope for growth in our correctional service. The bigger question for us, though, is why segments of our justice system are being used to extract profit for an international concern whose revenue totalled £4.9 billion ($9.5 billion) last year.
Are we being co-opted into a "prison-industrial complex" based on promises of great cost efficiency, only to find that those savings are not realised for New Zealanders, but used to buttress bigger and bigger dividend payments to Serco's shareholders?
The fact is that private concerns such as Serco are divorced from, but dependent on, the justice and other societal systems that deliver prisoners to them. Somehow, governments have been convinced that they can outsource the detention of citizens to private corporations that have completely different incentives.
In the end it is a question that's every bit as fundamental as the one about grass verges, charter schools and state asset sales: where should government responsibility end and corporate opportunism begin?