The Prisoners (Control of Release) (Scotland) Bill was brought forward by the Scottish Government to end automatic early release, whereby offenders were freed after serving two-thirds of their jail term.
Originally the Bill sought to end the practice for those serving sentences of more than 10 years and sex offenders serving more than four years.
But the legislation, if passed by MSPs at its final stage today, will now end early release for all offenders sentenced to more than four years.
Under the new law, where a parole board deems it necessary, those serving a long-term sentence will be kept in prison to serve their full term as opposed to being automatically released.
During scrutiny of the Bill, concerns were raised that prisoners could “max out” their sentences to avoid supervision when they get out, a situation described as “cold release”.
The Government brought forward an amendment which will see long-term prisoners released when they have six months left to serve, and then monitored in the community.
The blanket six-month approach was backed by the Scottish Parliament’s Justice Committee, but the Bill is likely to come under fire from some MSPs today.
Scottish Labour will seek to amend the legislation to give courts the power to decide what period a released prisoner should be supervised for.
The party’s legal affairs spokeswoman Elaine Murray MSP said: “Scotland deserves better than a uniform approach to justice, we cannot treat every offender the same and this must apply when they return to the community.
“It seems senseless that an offender sentenced to four years would be expected to be placed under supervision for the same length of time as an extremely violent or repeat offender, but that is what the Bill currently proposes.
“Scottish Labour will push to amend the Bill to give our courts the power to set the period of supervision, rather than treat every offender in the same way.”
The Conservatives, who want an end to automatic early release for all prisoners, have proposed an amendment which would allow the plans to be delayed and revisited.
The party’s justice spokeswoman Margaret Mitchell MSP said: “The SNP committed to abolishing automatic early release, but instead has brought forward half-baked plans.
“These proposals do not go far enough - they do not end automatic early release, and only affect around 3% of prisoners.
“The Scottish Government should postpone this while it can, and tomorrow is the last chance to do that.”
A Scottish Government spokeswoman said: “The Prisoners (Control of Release) (Scotland) Bill will, if approved by Parliament, help protect the public while ensuring a period of supervision in the community for all long-term prisoners leaving custody.
“The aims of the Bill are in line with the recommendations of the Scottish Prisons Commission (2008), to ‘target the use of prison where it can be most effective - in punishing serious crime and protecting the public’.
“While Parliament will have a chance to debate the Bill and the amendments, the Scottish Government considers that extremely violent or repeat offenders should serve more of their sentences in custody if that is what the independent Parole Board decides is appropriate in any given case, and that is what the Scottish Government’s approach will ensure.”