Cross-party consensus against prison sentences of less than a year is growing, with Scottish Lib Dems and Labour backing alternatives to custody.
Prison sentences of under three months are already avoided if possible.
Now a campaign to extend that to 12 months is building momentum after Scotland’s chief inspector of prisons came out in public yesterday in support of the move.
Scottish Liberal Democrat leader Willie Rennie and justice spokesman Liam McArthur said they will provide the majority the SNP needs for the reform.
Mr McArthur said: “Short term sentences are incredibly destructive, with more than half re-offending within a year of release.
“All the evidence shows that community-based justice programmes and diversion-from-prosecution projects are far more successful in reducing re-offending and healing communities than short stints in prison.
“Liberal Democrats will use our votes in Holyrood to support these measures if the SNP brings them forward.”
A Scottish Labour Party spokesman said Scotland already has one of the highest prison populations by head in Europe and the focus should be on rehabilitation.
He said: “Prison should always be a last resort and our most extreme sanction for unacceptable behaviour — it should never be a substitute for failing mental health services, or the withdrawal of funding from drug treatment centres.
“Our justice system should ensure sentences are proportionate and effective.”
But dissent came from the Scottish Conservatives shadow justice secretary Liam Kerr.
He said: “Short term prison sentences can play an important role in our justice system, and it would be ludicrous to end them.
“We cannot fetter judges’ discretion without full consideration of the consequences and wider policy context.
“There are many offences and circumstances where a custodial sentence of up to twelve months could be an appropriate punishment, and we need to allow judges the choice to hand down such sentences if they deem it necessary.”
A Scottish Government spokeswoman said short prison sentences were ineffective and work to provide alternatives was continuing.
She said: ““We have consistently stated that the consultation responses on extending the presumption against short prison sentences would inform our decisions and it is only right we take the time to consider these views. We’ll continue to discuss how best to take this forward with the relevant stakeholders.
“There will, however, always be some crimes where a custodial sentence is absolutely justified.”