Legal experts say a sentencing provision that can keep killers in prison for the rest of their lives is likely to make its way to the Supreme Court of Canada.

The federal government enacted legislation in 2011 that allows a judge to order a multiple murderer to serve consecutive periods of parole ineligibility for each offence.

It has only been applied on six occasions.

The most recent was in the case of Derek Saretzky, who was sentenced in August for the first-degree murders of a man and his two-year-old daughter as well as a senior in southwestern Alberta.

Saretzky received the mandatory sentence of life in prison. But instead of the usual 25 years before parole eligibility, the judge ordered that Saretzky spend at least three times that long — 75 years — behind bars before he can apply to get out.

"This case hammers home the stark reality of the law as it is now. If you want to make it consecutive, you've got to make it 75 for three murders," said Calgary defence lawyer Balfour Der, who is challenging Saretzky's conviction and sentence in Alberta's Appeal Court.

"We're talking about a 22-year-old who would end up with ... no parole until he's 97.

"If we look at it that way ... maybe we should give him a break. On the other hand, this is a very serious crime. This is highly emotional because of the circumstances of the deaths and who are the victims."

Cruel and unusual?

Der said it's a tricky legal issue.

"One of the grounds of appeal will likely be that the consecutive minimums of 25 years amounts to cruel and unusual punishment and, because of that, the section is unconstitutional."

He suggests a sliding scale for consecutive parole ineligibilities that still recognizes the seriousness of a case.

A University of Calgary law professor said she wouldn't be surprised if the case shows up in Canada's top court.

"I don't know how or in what manner the court would deal with it, but I would suspect it will happen," said Lisa Silver.

She said she can understand the argument since it's a relatively recent provision in the Criminal Code.

"It does mean that someone is spending an amount in custody that was unheard of in the past," Silver said. "It is something that the Supreme Court of Canada needs to look at and needs to determine once and for all. Is this constitutional?"

'Useful tool'

Veteran Calgary defence lawyer Alain Hepner expects the provision will get a second look by the federal government.

"That's the U.S. model," he said. "It's not too extreme from a public perception, but ... the case law and the judges say we're not here to pander to the public opinion. We have to apply the law.

"A lot of these people may never see the light of day and the public may want that. There's got to be other ways of doing it."

Alberta's justice minister said consecutive parole ineligibilities can be a "useful tool" as a signal to criminals that multiple crimes may lead to a longer sentence.

"It can potentially have a beneficial effect in terms of signalling to people who are doing these things that it's not a good idea," Kathleen Ganley said.

"It can have a sort of deterrent effect. That being said, obviously it's only intended to be used in certain circumstances."