PM has forgotten what diverts young offenders

The £5bn announcement centres on hiring 20,000 extra police officers, building 10,000 more prison places, and an expansion of the stop and search provision. Very law, very order.

No one wants to see crime occur without any apparent response from the police, as it does too often at the moment. An hour spent with a child in trouble will quickly convince you that the threat of detection - not punishment, mind, just getting caught - is a major element in building desistance. The risk of 20,000 extra officers comes not from extra detection but from what might happen next. This is the "scare 'em straight" approach, the one criminal justice programme that has most spectacularly failed wherever tried.

What we have learned over the last 15 years in England and Wales is that diverting children who misbehave from the criminal justice system reduces the number of children who later develop serious offending records. At its heart this is about the dangers of labeling and stigmatising that accompany contact with criminal justice agencies. Large-scale planned reductions in numbers of first-time entrants - an 86 per cent fall over little more than a decade - has been followed by large reductions in imprisonment, producing a 73 per cent reduction in the numbers of children in custody.

Proof that this is not just a case of "justice postponed" is provided by a smaller, but still obvious, fall in the numbers of young adults coming before the court or ending up in prisons. The lesson from this is… most children who are diverted from trouble stay diverted as they grow up.

We have been here before, although not everyone will remember this. In 2004, the New Labour government ill-advisedly introduced its "offences brought to justice" programme, designed to reduce the "justice gap" between offences reported and offences brought to court. This had disastrous consequences for the children caught in the crossfire of political spin. Interpreted in many places as "round up the usual child suspects", the net of the youth justice system widened and the number of children in custody reached an all-time high.

The goal of justice policy for children has to be to divert them away from the risk of long-term offending, with all the harm that entails for them and the communities in which they live. So while it is possible to think of very useful roles for 20,000 extra police officers, with more restorative justice, community-based policing, a fuller integration in multi-agency youth justice and safeguarding teams as examples, the linking of extra police with extra imprisonment is precisely the wrong direction to be headed. Will someone please let the Prime Minister know?

• John Drew is senior associate, the Prison Reform Trust