Of the people sent to overcrowded prisons by British courts, two thirds are given a sentence of less than 12 months, taking valuable resources away from serious offenders from whom the public need protecting.

The number of people receiving custodial sentences has risen inexorably in the past ten years — we now lock up people who ten years ago would never have fallen into the prison net.

Research shows that short-term prison sentences do not work. Reoffending rates remain persistently high for low-level offenders given custodial sentences, and locking them in cells is costing the State millions each year.

Although the Ministry of Justice has dropped the £3 billion plan to build three Titan prisons, six new “mini-Titans” are still planned at an even higher cost to the taxpayer. We need to stop locking up low-level, non-violent offenders on short-term sentences.

Instead, we must invest in more effective community-based sentences that help to pull those offenders back into society and away from crime.

Such a policy has already begun to take hold in the United States where there is a growing realisation that locking people up briefly is expensive, intensifies offending and does not work as punishment. In Scotland the ruling SNP stated its intention to phase out prison sentences of less than six months, replacing them with tough community sentences.

And, next week, the Transition to Adulthood Alliance, a group including virtually every significant justice policy organisation in Britain, will publish its latest findings, which will also call for a review of the policy of locking up any 18 to 24-year-old for less than six months.

But in England and Wales the “lock ’em up” culture remains an intractable government policy. After 18 months of an economic downturn and last week’s spending review, it seems bizarre that, although other public services are coming under massive scrutiny, the Government is not willing to accept that short-term prison sentences are costing society billions each year.

We commissioned Matrix, an independent economic researcher, to undertake a study of one group of low-level offenders who make up a huge proportion of those who receive short sentences: drug users. We asked Matrix to study the cost benefit of locking up this group against diverting them onto robust community-based sentences that include intense drug treatment. The figures were astounding.

About 7,873 drug users were given sentences of less than 12 months in 2007, making up almost 10 per cent of the total number of offenders sentenced to prison that year. Our research suggests that society would have saved almost £1 billion had these drug-using offenders been given residential drug treatment instead of simply being thrown into a cell.

We are not calling for a root-and-branch change in Britain’s prison system. We are calling for a commonsense approach that is solvable and appropriate to the problem. We have evidence to prove that short-term sentencing does not work and that properly resourced community-based sentences do. Low-level crime is devastating to its victims, but blindly locking up offenders doesn’t give anyone a long-term payback.

• Roma Hooper is the founder and director of Make Justice Work

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