The Liberal Democrats have demanded action after more than 1,000 prisoners on short sentences spent Christmas behind bars last year.
The Scottish Government has pledged to extend the current presumption against short sentences of six months or fewer to 12 months.
Scottish Liberal Democrat justice spokesman Liam McArthur criticised the time taken to act since the Scottish Government consulted on the extension more than three years ago, in which 85% of respondents backed the proposal.
Scottish Prison Service figures given to the party through a freedom of information request show 1,022 prisoners on sentences of a year or less were behind bars on Friday December 22, 2017, meaning they would spend Christmas there.
The total prison population on that date was 7,332.
Mr McArthur said: “Last year over 1,000 people were behind bars at Christmas due to a short-term sentence.
“Rather than being given short spells in prison, such offenders would be better serving tough, community-based sentences.
“We know that 60% of people given ineffective and disruptive short-term sentences re-offend within a year of release, whereas robust community-based sentences are far more successful and reduce the chance of more people becoming victims of crime.”
He said community sentences are “not soft options” but help preserve family ties and limit the damage to the children of those behind bars.
“It is over a decade ago since the Prisons Commission concluded people on short sentences are “more troubling than dangerous” and three years since the consultation on extending the presumption against short sentences closed.
“Responses were overwhelmingly in favour of this shift, with experts including HMIPS (Her Majesty’s Chief Inspector of Prisons for Scotland) backing a new 12-month rule.
“In her Programme for Government the First Minister committed to taking these measures forward.
“However, it is now important that she holds her nerve and follows through on that promise.”