Risdon Prison's overcrowding headaches are tipped to magnify further on the scrapping of early release for well behaved inmates.
Tasmania's Upper House of parliament's waved through the government's change.
An inquest is examining the case of North Hobart shopkeeper Voula Delios being stabbed to death by a mentally ill man released from jail early.
Greg Barns from the Prisoners Legal Service says politicians motives behind the change are self serving.
"The real villain in this is the Australian Labor Party which earlier this week said it would vote on the basis of evidence, it decided that populism, putting politics and votes before good policy got too much for it and it flipped this week."
The Liberals are pushing to end early releases on the basis it's been phased out interstate.
Mr Barns says scrapping it could potentially do more harm than good.
"The issue with remissions is that it provides a very good incentive for behavioural change on the behalf of prisoners, what's going to happen now is it's going to increase tensions in an overcrowded, underfunded and understaffed prison system."
"This decision taken by the parliament flew in the face of all the advice they got and in particular a very eloquent address by an ex prisoner on Wednesday at a briefing. What's happened here they've decided to take the populous path rather than looking seriously at the question of why remissions are so important."