The head of West Yorkshire Probation has called on the Government to scrap prison sentences of less than six months.
Mark Siddall, director of operations, said the move would save billions of pounds and cut crime rates overnight.
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In a scathing attack on the current court sentencing arrangements, he said jail terms of less then six months did more harm than good to both society and offenders.
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He wants to see most short-term sentences replaced by community service orders.
At any one time, the Probation Trust deals with around 12,500 people on court orders, about 5,000 of whom undertake community payback – unpaid
work in the community – worth about 2.6m.
The trust also deals with more than 2,000 'high risk' offenders, including those convicted of violent, sexual and terrorist related offences under a scheme called MAPPA (Multi Agency Public Protection Arrangements).
This is a joint operation involving the police, prisons and local authorities, and health trusts .
Mr Siddall said: "A short term prison sentence is the worst of both
worlds – it is short enough for the criminal to lose his job, his home and his personal relationships but not long enough for us to do anything useful with them.
"Community orders are nearly twice as effective as short term prison sentences, not to mention a lot cheaper.
"In terms of re-offending rates, 61 per cent of those released from a short term prison sentence will go on to re-offend, whereas the same figure with community service orders is 36 per cent - almost half.
"In terms of cost, the average cost of a prison place is 45,000 a year. If you are in high security its much more, Whereas, the average cost of a supervision order is 650.
"So, not only are they nearly twice as effective, they are significantly cheaper. Even an expensive community order only costs
about 5,000. To me, it's a no-brainer.
"Every time I hear of someone who has been given a sentence by the courts of three or six months in prison, I think to myself, why did you choose to punish them in that way - it simply doesn't work."
His comments come as the Government pushes ahead with plans to privatise part of the probation service - bids are expected by the end of the year.
The prison population stands at around 85,000, over three-quarters of which is composed of people serving sentences of 12 months or less.
Justice Secretray Ken Clarke has already indicated he would like to see a reduction in short-term sentencing but no laws are due to be passed which would enable that to happen.
Mr Siddall said: "The most effective way would be to give guidance to courts but governments are reluctant to be seen interfering with courts. They have a plan in Scotland to ban prison sentences under six months and the Lib Dems had a manifesto pledge to abolish under six month sentences but whether that will happen is another matter.
"About six years ago the Government published some estimates on how much it would cost to manage these additional offenders and it came out at something like 3bn, which was deemed too high.
"However, compared to the estimated cost to society of re-offending, which was 10bn when the estimates were done, it's worthwhile."