There are more than 300 prisoners on home detention curfew
MSPs have approved plans to extend electronic tagging for long-term prisoners.
It means some serious offenders will be freed from jail and confined to their homes at night using electronic tags.
Justice Secretary Kenny MacAskill gave assurances that only prisoners already cleared for parole would be affected.
The Tories warned that it could lead to a tragedy like the Robert Foye case in which an offender absconded from an open prison and raped a young girl.
This was the Scottish Government's third attempt to have the plans passed.
The last attempt failed after four Lib Dems, who supported the move, voted the wrong way in parliament and two others failed to vote at all.
Ministers were seeking the extension for prisoners on parole in a bid to reduce prison overcrowding.
The Conservatives and Labour were opposed to the move.
The government had already won approval to tag short-term inmates for longer, under the home detention curfew (HDC) scheme.
Ministers pointed out Scotland's prison population had reached record levels of about 8,000, compared to a design capacity of 6,626.
Mr MacAskill earlier said powers to release long-term prisoners on home detention curfew licence already existed.
He said rejecting the new measures would mean standard conditions not being imposed on all long-term prisoners.
"That will not prevent the release of long-term prisoners on HDC," he told the Scottish Parliament.
Tory justice spokesman Bill Aitken said the measure showed the justice secretary was failing in his duty to apply the degree of deterrence necessary.
He said the proposals demonstrated "a naivety which I find disturbing".
Labour justice spokeswoman Pauline McNeill also expressed concern, adding: "We are being asked to do this immediately for the single purpose of reducing the prison population."
Lib Dem justice spokeswoman Margaret Smith, whose party backed the government proposals, said that 40% of those who applied to be released from prison early under the scheme were refused.
She said 69% of those freed under tagging did not breach the conditions imposed, adding that most breaches were for "minor reasons".
"It should also be looked at as a positive option for those prisoners who are assessed as being low risk so they can integrate back into their community in a managed way," she said.