Ram raids are one such crime. They are down 85%.

There could be several reasons. More children are back at school. There are more police.

Shopkeepers have installed bollards and other barriers. My local dairy, after being repeatedly ram-raided, now resembles a fortress.

Whatever the reasons, understanding them matters. Keeping the peace is the first duty of Government.

I have seen youth offending from several perspectives. As a lawyer, I represented young offenders.

As a university student, I spent a summer working nights at the Ōwairaka Boys’ Home. Later, I became Minister of Police.

I suspect deterrence has played a larger role than many are willing to admit.

Under the previous Government, young offenders knew there were few consequences for serious offending.

Our local dairy was ram-raided by youths from Hamilton driving stolen cars. They were caught, released and, less than two weeks later, returned in stolen cars to ram-raid the dairy again.

It used to be very different. The ultimate consequence for persistent young offenders was the Boys’ Home. Progressive campaigners eventually succeeded in closing it, portraying it as a brutal institution.

That description bore little resemblance to the place I knew.

The Ōwairaka Boys’ Home stood in suburban Mt Albert. It looked like a large wooden house surrounded by lawns. There were no bars on the windows, no razor wire and no imposing security fences.

There were about 40 boys. It was more like a well-supervised boarding school, except the food was better and bullying was not tolerated.

Critics often pointed to the two “cells”. They were not punishment cells but closely supervised timeout rooms, used rarely.

Part of my job was admitting boys brought in by the police late at night. Many had spent days on the run after fleeing homes marked by violence, neglect and abuse.

It was not unusual for a newly admitted boy to sleep for 24 hours.

No boy would ever admit he liked the Boys’ Home. Three meals a day, a bed every night and clear rules were not the image they wanted to project.

Quite the opposite. They exaggerated how terrible it was. Every story made its reputation more fearsome.

That reputation mattered.

I doubt many boys who reached the Boys’ Home were rehabilitated. By then, most had already lived through years of neglect and had become habitual offenders.

We should never stop trying to turn young lives around. But rehabilitation is not the criminal justice system’s only purpose.

Its other purpose is deterrence.

The real measure of the Boys’ Home was never how many boys who went there offended again. The more important question was how many boys never went there because they feared being sent there.

The same question should be asked about today’s bootcamps.

Critics point to those participants who have reoffended. That asks only half the question. Given that around half of adult prisoners are reconvicted within two years, I am not surprised that the bootcamp reoffending rate is high.

The more important question is how many young people decided not to offend because there is once again a meaningful consequence for persistent offending.

When one of my sons attended Avondale College, a student in his class was expelled for bringing alcohol to school.

I told the legendary principal, Phil Raffles, that my son thought the boy was more foolish than wicked.

“Perhaps,” he replied, “but every student knows the rule. My responsibility is to the other 2000 pupils.”

At the time, Avondale College was one of New Zealand’s largest secondary schools, attracting many from out of the zone. Parents wanted their children to attend a school that was well run and drug-free. I certainly did.

That is how deterrence works. The punishment imposed on one person influences the behaviour of many others.

Deterrence works through the crimes that never occur.

We see the crimes that happen. We do not see the crimes that never happened.

There are no victims, no headlines and no police reports. There is nothing to count except the absence of crime.

We know ram raids have fallen by 85%. We can measure that. We cannot measure the countless offences that were never attempted because potential offenders decided the risk was no longer worth taking.

Deterrence is one of the few public policies whose greatest successes are, by their very nature, invisible. We count the crimes that occur. Good policy also requires us to think about the crimes that never happened.

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