The justice sector is not coping with National's budget cuts. This is apparent even from the redacted version, where they talk about having operated within flat baselines for the last two years. But two years of effective cuts through inflation has a price, and MoJ now says the justice system is "under some pressure" (p. iv). On page 12 they go into more detail, saying explicitly that "sector performance will be constrained without new resources":
Despite significant progress within flat baselines, under the existing operating model and without new resource, the sector’s ability to continue improving performance is constrained. The current operating model (with fixed numbers of police, and a nation-wide network of courts and prisons) is likely to cost at least $140 million more than current baselines by 2017/18. Sustaining an effective and trusted justice system requires a level of baseline funding that is now under considerable pressure.That's how National is goign to achieve its "surplus": by putting off costs for future years and leaving the resulting problems for the next government to sort out. But under any honest system of accounting deferred maintenance is not a real saving - and that's basically what this is: they're running down our core government institutions, such as the court service, in pursuit of an arbitrary budget target.
The Ministry of justice believes we are not treating teenage offenders properly. They're quite explicit about this:
Currently the adult criminal jurisdiction begins at 17, which is out of step with comparable jurisdictions and international legal obligations. Evidence suggests better long term justice outcomes (reduced lifetime offending) and social and economic outcomes (improved skills and employment prospects) could be achieved by dealing with 17 year olds in a different way to adults.
And later:
For teens, more punitive approaches to offending can disrupt skill development and lifetime employment outcomes. New Zealand is out of step with comparative jurisdictions and international obligationsin this area. There is therefore value in reviewing the current boundary between the youth and adult criminal system (17 years).
You can see why this was censored: National loves to bang the "law and order" drum, and young people make an easy target (especially when those young people are browner than the scared Pakeha pensioners National are trying to appeal to). But its not good policy and it violates the United Nations Convention on the Rights of the Child - the most widely accepted international human rights instrument in the world. But if we don't want to condemn kids to a life of crime, then we need to act on this.
Meanwhile I expect people will be taking a closer look at other BIMs. Sadly, none of the ones I've checked have similar problems.