Judges and sheriffs should be be limited in the sentences that they can impose in an attempt to tackle overcrowding in prisons and reoffending, according to a senior Scots lawyer.

John Scott, chairman of the Edinburgh Bar Association and chairman of the Howard League for Penal Reform in Scotland, said judges and sheriffs should be banned from passing jail sentences of less than 12 months.

Mr Scott's unprecedented call came on the eve of today's long-anticipated Prisons Commission report. The independent commission, headed by Henry McLeish, the former First Minister, is expected to recommend tougher community sentences to try to build public confidence in the penalties and encourage their use by the courts.

Mr Scott said that more radical action was required to force the judiciary to impose community disposals. “What I am hoping for is a statutory prohibition on issuing sentences of lower than 12 months,” he said.

“People have a misplaced confidence in prison as the answer to everything, including the sentencers - everyone is in prison because a sheriff or judge has decided that they should be there - but sentences less than 12 months don't do anything. They can even be counterproductive as prison officers are prevented from working with more serious offenders.”

Mr Scott admitted that restricting the discretion of the judiciary would be controversial, but argued that that was no reason to dismiss it out of hand: “Any attempt to [ban short-term sentences] would be seen as interfering with their independence, but we should not shy away from this.

“Unless sheriffs, stipendary magistrates and judges are told you cannot send people to prison for less than 12 months nothing will change.”

The Prisons Commission was appointed last year amid concern over the country's soaring jail population and fears that overcrowding is preventing effective rehabilitation. After reaching a record of 7,497 last year the number of inmates has continued to rise, reaching 7,642 as of last Friday, while figures issued last month showed that 62 per cent of those discharged from custody proceed to reoffend within two years.

As more than 80 per cent of all custodial sentences awarded last year were for six months or less, Kenny MacAskill, the Scottish Justice Secretary, favours greater use of community penalties for minor offenders but they remain unpopular with critics, who say they are a soft option.

Despite the continuing search for a solution, Bill Aitken, the Scottish justice spokesman for the Scottish Conservatives, said that abolishing short-term sentences was not a credible alternative.

“I'm afraid this simply wouldn't work,” he said. “We have to think of the wider society and frankly we need a rest from the activities of those who break into our houses, commit acts of vandalism, and disturb the peace. Mr Scott speaks for the criminals; the rest of us speak for the victims.”

A spokesman for Mr MacAskill said the minister was aware of the problems surrounding short sentences and intends to raise the matter with the judiciary. He said: “The independence of the judiciary is a fundamental cornerstone of the Scottish criminal justice system and we attach great importance to judicial discretion in individual sentencing decisions.

“However, we do believe that there is a case for sentencing guidelines to help deliver more consistent and transparent sentencing and improve public confidence in the criminal justice system. We plan to hold further talks with key interests, principally the judiciary, on how to achieve this, including the arguments for the creation of a statutory sentencing council.”

He added that Mr MacAskill was looking forward to the recommendations of the commission and would bring forward proposals as quickly as possible.