The Conservative government has unveiled new legislation that proposes life sentences without a chance of parole for Canada鈥檚 鈥渕ost heinous criminals.鈥

Prime Minister Stephen Harper announced the new tough-on-crime legislation in Toronto on Wednesday. The measures would force some violent offenders to wait 35 years before applying for parole, adding a decade to the current wait time.

The proposed law would apply to individuals convicted of first-degree murder involving the killing of police or correctional officers; terrorism; kidnapping or sexual assault. Harper said the legislation would also apply to crimes of a 鈥渂rutal nature鈥 and high treason.

鈥淥ur legislation will permit a killer serving life without parole to voluntarily petition the minister of public safety for release after serving no less than 35 years,鈥 Harper said.

Should the individual request parole, the decision would rest not with an appointed parole board, but with the federal cabinet, who Harper said would be 鈥渇ully accountable to their fellow citizens and to the families of the victims of these crimes.鈥

Under the current law, individuals convicted of first-degree murder receive an automatic sentence of life in prison, with no chance of parole for 25 years.

Critics denounced the legislation Wednesday, saying the changes are unnecessary and could set a dangerous precedent.

Liberal Leader Justin Trudeau said Canada鈥檚 current system already 鈥渞ecognizes鈥 that killers such as Paul Bernardo and Robert Pickton should not be released.

鈥淚 think a lot of this is campaigning on fear, which (Harper) is extremely good at, but I think we can all agree that bad criminals should not be released and we have to make sure that we鈥檙e getting that balance right,鈥 Trudeau said.

But Justice Minister Peter MacKay said the legislation sends a message of consistency and closes gaps in the Criminal Code "with respect to the worst of the worst.鈥

Wednesday that an individual convicted under these new provisions would 鈥渄raw their last breath behind bars.鈥

鈥淲e would hope that we would never have to use these provisions, but let鈥檚 be honest: There have been examples of this type of extremely violent, heinous crime in Canada,鈥 MacKay said.

Apart from sending a message of deterrence, MacKay said the legislation provides security for families of victims who are 鈥渞e-traumatized鈥 by ongoing parole hearings.

But some prison law experts said the crackdown effectively eliminates any possibility for criminals to rehabilitate.

Queen鈥檚 University law professor Allan Manson said it鈥檚 unclear what the legislation is trying to achieve.

鈥淭he most heinous cases do not get out so this is not an issue of whether the Clifford Olsens will be released,鈥 Manson said, referring to the convicted serial killer who confessed to murdering 11 children and youth in the 1980s.

Manson also said that the legislation is 鈥渘ot in step鈥 with jurisdictions that are 鈥渟erious about crime but also respect human rights.鈥

Canada鈥檚 Correctional Investigator Howard Sapers said the legislation will increase overcrowding in prisons. Each year, between 30 and 60 individuals receive a life sentence for first-degree murder, he said, so the lengthier terms will lead to a 鈥渟tacking effect.鈥

鈥淚t will become nothing more than a holding pen because there鈥檚 no point in preparing these people for release, there鈥檚 no point in engaging them in vocational programming,鈥 Sapers told Power Play.

There is also some research that suggests very long sentences contribute to criminality, Sapers said.

鈥淲hen you take all hope away from somebody, you don鈥檛 give them any incentive to follow rules or be at all productive.鈥

Charter challenge?

Manson said that a legal challenge could be successful, should one be filed.

鈥淚f there鈥檚 no penological objective, we now have a provision that is arbitrary, so I think that there are at least two grounds with which the Supreme Court could look at this and chuck it out.鈥

The bill, the latest in a series of tough-on-crime proposals by the Conservative government, is expected to be tabled next week in the House of Commons.