A new report on sentencing published today makes the proposal after the number of prisoners in Scotland reached record highs last year.
And earlier this week Justice Secretary Angela Constance announced there would be more early release, with some prisoners on sentences of less than four years getting out after serving just 30 per cent of their sentence.
Now the Scottish Sentencing and Penal Policy Commission, which has been looking at ways to solve the issue in the long term, says the government should extend its presumption against short sentences to 24 months.
Under the current policy, Scotland's judges are discouraged from issuing custodial sentences of less than a year.
The proposal was slammed by the Scottish Conservatives who said it would give a "free pass" to criminals and was a "gross insult to victims".
But chair of the Commission, Martyn Evans – a former chairman of the Scottish Police Authority – said reform was needed as Scotland's justice system is at a "critical moment".
"Prison should be for serious and dangerous offenders, not for people who need help, support or simply a second chance," he said. "We need to choose a different path – one that uses imprisonment more wisely, reduces reoffending and strengthens community responses."
Laying out the rationale around ending sentences of two years or less, the report says: "When passing a sentence of fewer than 24 months, members of the judiciary should provide a written note of all the available alternatives considered and why, bearing in mind the particular facts and circumstances of the case, no other method of dealing with the person was appropriate.
"Data on the reasons provided should be gathered in a format that is amenable to systematic collation and analysis."
Around a quarter of the country's prison population is on remand, having not been convicted of a crime, but the Commission recommended only those with a prospect of being sent to jail upon conviction for more than two years should be held on remand.
A national "decarceration" plan should also be published within the next year to set out "clear milestones" to bring down the rate of imprisonment in Scotland, along with considering the establishment of a new inspectorate which will look at the "administrative performance of the criminal courts".
The Government should also develop a policy on "transitional accommodation", designed to help those leaving prison stay off the streets.
Scotland's prison population stood at a record 8420 last October, but by the start of February had fallen to 8301.
A programme of emergency early release has also resulted in more than 400 prisoners being freed in recent months.
Despite that, and the increased use of alternatives to prison and increases to prison capacity, eight jails are still at "red-risk status", with 15 close to or over capacity.
Martyn Evans added: "Our commission report sets out ambitious recommendations to deliver system-wide reform.
"By transforming our justice system, we can create a fairer and more effective society for all of us.
"Our report addresses the full journey through the justice system, from prevention and early intervention through to sentencing, rehabilitation and reintegration into communities.
"At every stage, our focus has been on what works to rehabilitate and reduce harm, improve lives and strengthen public safety."
But Scottish Conservative justice spokesman Liam Kerr said increasing the presumption against short sentences would give a "free pass" to criminals.
"It is another gross insult to victims who are a complete afterthought when it comes to the SNP's justice priorities," he said.
"This comes in the same week when the SNP's Justice Secretary already confirmed she wants to let more criminals out early. Now if she agrees with these recommendations, many dangerous criminals will spend no time behind bars at all.
"The SNP's reckless approach is only continuing to endanger public safety across Scotland."
Mr Kerr said he has written to Ms Constance, claiming the report was more a "strategy to empty the prisons, regardless of the consequences" than a "plan to improve justice".
Labour's justice spokeswoman Pauline McNeill said: "The SNP cannot keep letting criminals dodge jail in order to manage the chaos they have created in our prison system.
"Sentencing should be about how we keep communities safe – not how we clean up the SNP's mess.
"Angela Constance and the SNP have pushed our entire justice system to breaking point – from frontline policing to our courts to our prisons. The SNP's sticking plaster solutions and soft touch approach to justice is letting Scotland down."
But Justice Secretary Angela Constance welcomed the report, and said: "The breadth of recommendations requires detailed consideration and prioritisation. Taking this forward will be a matter for an incoming government, with many requiring legislative change.
"Bold, collaborative action is needed to reduce reliance on custody and achieve a sustainable prison population. We are committed to taking action.
"There is no silver bullet but these considered recommendations can help us achieve a sustainable prison population.
"We remain an outlier in prison numbers. While prison will always be necessary, we need to shift the balance to community justice, which is shown to reduce reoffending and be more cost-effective for the public purse.
"I will consider the detail of the report and set out my in-principle response to the report in a statement to Parliament next week."
