PLANS to increase a presumption against short jail sentences will do little to reduce Scotland's huge prison population, one of the country's leading criminal justice experts has said.

Cyrus Tata, Professor of Law and Criminal Justice at the University of Strathclyde, said Scottish Government proposals were unlikely to have a meaningful impact and today called for a wholesale change in the role of custody in society, criticising that a rising prison budget accounts for ten times the spend on community rehabilitation services.

In a paper published in the Scottish Justice Matters journal, he said that a mentality and policy of seeing 'custody as the last resort' must be ditched if there is to be a significant reduction in Scotland's prison population, which is among the highest in Western Europe.

He said that some offences should be specified as "normally non-imprisonable" while jail sentences should no longer be passed for minor crimes in order to provide services for people with health, addictions and other needs.

The Scottish Government has recently consulted on extending a current presumption against three months sentences to six, nine or 12 months with Michael Matheson, the justice secretary, describing the number of people jailed as "totally unacceptable".

However, Professor Tata said that the three month policy “has had little impact on sentencing decisions” a fact the Government has acknowledged in its own research, with courts either sending criminals to jail for slightly longer or having to merely provide "terse, bland or uninformative" reasons for going against the presumption.

He warned that the same ineffectiveness would continue under an extended presumption and that instead, a mindset that sees judges and sheriffs fall back on imprisonment as they see it as a "dependable, credible and well-resourced back-stop" should go.

He argued that people are often jailed as stretched community services are not considered capable of dealing with deep-seated personal problems such as substance abuse, mental health issues or homelessness, rather than because they were dangerous or had committed particularly serious crimes.

He said: "It is not entirely uncommon for people to say that they would prefer to be in prison because of a lack of help and support in the community. That is, surely, an indictment of our spending priorities.

"The result is self-perpetuating: resources are sucked into the seemingly credible, robust and reliable option of imprisonment at the expense of community-based programmes which appear as weak, unreliable and poorly explained.

"This phenomenon will become even more acute, unless action is taken to preclude it. We will soon see further deep cuts to community justice and community services. Meanwhile, prison regimes are improving. One cannot necessarily, therefore, blame individual sentencers, prosecutors, social workers for seeing imprisonment as the only ‘safe haven’ for individuals presenting with deep-seated and complex needs. Yet in policy terms it is a senseless waste of resources and human potential."

A string of expert groups have recently called for the presumption to be extended to 12 months, a move backed by Mr Matheson's predecessor Kenny MacAskill.

Evidence suggests that short prison sentences disrupt the lives of offenders to such an extent that they are far more likely to get into further trouble on release, with the length of time they spend in jail insufficient to tackle their issues.

Professor Tata suggested that an 'imaginative' use of electronic monitoring - including GPS - alongside traditional criminal justice social work could be used in cases where community sentences are breached, rather than imposing custody instead. He said monitoring could become the 'ultimate sanction' for some low-level offenders rather than jail.

The Scottish Government said it was "working towards" a situation where prison was used less frequently, with a greater emphasis on strong community sentences which do more to tackle causes of offending.

A spokeswoman added: "Currently 60 per cent of offenders imprisoned for three months or less are re-convicted within a year. Extending the presumption would give a clear signal that custodial sentences should be reserved for people whose offences are so serious that no other form of punishment will do, and for those who pose a threat of harm to the public."