On the eve of the third anniversary of the Quebec City mosque shooting, lawyers will begin arguing whether the shooter's prison sentence — 40 years without parole — is too light and imperils Canadians, or too harsh and violates his charter rights.

Alexandre Bissonnette's lawyers and attorneys for the Crown are both appealing the sentence Bissonnette was given last year. Each side will present their arguments in Quebec City on Monday before justices of the Quebec Court of Appeal.

Bissonnette's original sentence followed his pleading guilty to six counts of first-degree murder and six counts of attempted murder, representing the victims of his Jan. 29, 2017, attack on a mosque in suburban Quebec City.

In handing down the sentence, Superior Court Judge François Huot had the option of giving Bissonnette the longest prison sentence in Canadian history.

Under a Criminal Code reform passed by Stephen Harper's Conservative government, Huot could have ordered the shooter serve his six life sentences consecutively. That would have meant a 150-year sentence before Bissonnette could apply for parole.

But Huot took the controversial step of ruling that amended section of Criminal Code (745.51) unconstitutional. He gave Bissonnette five concurrent 25-year sentences.

To that, he added an unusual 15-year term for the sixth count of first-degree murder.

Sentence fails to protect Canadian society: Crown

The sentence dismayed many in Quebec City's Muslim community, including survivors of the shooting, who felt it was too lenient and didn't adequately capture their suffering.

On Monday, lawyers for the Crown will argue that failing to give Bissonnette a harsher sentence makes Canada more vulnerable to similar hate-based attacks committed by lone actors.

Six men died in the attack on the Quebec Mosque. They are, clockwise from left, Mamadou Tanou Barry, Azzedine Soufiane, Abdelkrim Hassane, Ibrahima Barry, Aboubaker Thabti and Khaled Belkacemi. (CBC)

"The current case is of capital importance because it poses a precedent for mass killings motivated by prejudice and hatred against a religion in Canada, as well as integrating the 'lone wolf' phenomenon," reads an appeal document filed by the Crown.

"Canadian courts ... have to react adequately to protect Canadian society from a possible repeat of these tragic events," the Crown says. Bissonnette's sentence doesn't meet this "fundamental need," the appeal reads.

In order to meet that need, the Crown says Bissonnette should serve 50 years before he is eligible for parole. That would make him 77 years old before he can apply.

Parole is only granted if a prisoner can prove they are not an "undue risk to society."

'Cruel and unusual treatment or punishment'

Bissonnette's lawyers will argue that having to wait 40 years to apply for parole amounts to "cruel and unusual treatment or punishment," a violation of Section 12 of the Canadian Charter of Rights and Freedoms. They want Bissonnette to be eligible for parole after 25 years.

His legal team's brief to the court notes that at 25 years, life sentences in Canada are already among the longest in the world.

The brief says sentences longer than that can cause serious psychological damage and hinder an offender's ability to reintegrate into society after their release.

It adds that Canadian penal philosophy is based on the principles that criminals can "leave their criminality behind them" and that "offenders can pay their debt to society, ask for forgiveness and reintegrate into society."

Crown prosecutors Thomas Jacques, left, and François Godin will argue that a harsher sentence for Bissonnette will do more to protect Canadians from similar attacks in the future. (Jacques Boissinot/The Canadian Press)

In arguing for a lighter sentence, Bissonnette's lawyers are also expected to present new evidence, including security camera footage of the 2017 attack.

The video, according to the document submitted to the appeals court, will show that Bissonnette did not shoot in the direction of the children who were in the mosque. (Huot singled out the presence of children in his justification for the 40-year sentence.)

The new evidence is part of a broader effort to take issue with Huot's characterization of Bissonnette as a calculated killer who was motivated by racism and hatred of Muslims.

Bissonnette's lawyers will argue that he was, instead, someone with a long history of mental illness, and only embraced anti-immigrant and anti-Muslim views as a way of justifying his already violent desires.

'Brutal' timing

Bissonnette will not be attend Monday's hearing. But members of Quebec City's Muslim community are expected to be there.

Mustafa Farooq, head of the National Council of Canadian Muslims, said the timing of the hearings, just ahead of Wednesday's anniversary of the attack, is "brutal."

Farooq recently visited with several families of the victims. He said they are concerned about the outcome of the appeal; the mere prospect of Bissonnette's eventual release is "traumatic" for them.

"Many of the widows that I spoke to can't sleep at night. They don't visit the mosque anymore because of the constant fear associated with such a place," Farooq said.