The high court agreed Thursday to hear a pair of Crown appeals of Ontario cases in which the province's Appeal Court struck down the law, ruling it constitutes cruel and unusual punishment.
The sentencing laws increased the mandatory minimum sentences for possession of a loaded, prohibited firearm from one year to three years for a first offence and five years for a second offence.
The changes were enacted as part of the Conservative government's 2008 omnibus bill and the Supreme Court case will be a test of the Tories' tough-on crime agenda.
The decision to hear the mandatory minimum cases comes a day before the Supreme Court is set to rule in another Conservative sentencing law case. A decision is due out Friday involving the interpretation of a law that seeks to limit the amount of credit offenders get for time spent in custody before they are sentenced.
The mandatory minimum cases will be another test of the Tories' tough-on-crime agenda, amid some pushback from the courts.
The Supreme Court found last month that a retroactive change to parole eligibility was in clear breach of the Charter because it imposed new punishment on people who had already been tried and sentenced.
Judges in at least three provinces have either refused to order criminals to pay a mandatory victim surcharge or found ways to make it impossible for authorities to collect the fee as they say it places an unfair burden on those who don't have the means to pay.
The Conservatives have made significant changes to crime laws, especially in the area of sentencing, said University of Ottawa law professor Carissima Mathen, and they're being challenged on the basis of the Charter.
"I think it's part of the inevitable progress through the judicial system of various aspects of the Tories' tough-on-crime agenda," she said.
"I think this is likely going to be one of the most important pillars because it really gets to the heart of criminal justice in terms of what are the limits of Parliament's power to set sentences for criminals."
As usual, the Supreme Court gave no reasons for agreeing to hear the mandatory minimum appeals.
The court has often upheld mandatory minimum sentences, said Mathen, except in a significant ruling from 1987. In that case the court struck down a seven-year mandatory minimum sentence for importing narcotics.
A youthful first offender crossing the border with a joint could have been captured by the sentence, and a seven-year sentence would be cruel and unusual, the court found.
The difference between that case and the mandatory minimum cases the Supreme Court has upheld is underlying criminality, Mathen said.
"They often involve cases where the mandatory minimum is based on a situation where you're already committing a crime and then you cause some other consequence, so often causing death," Mathen said.
The drug case was simple possession, plus crossing the border, which is similar to the current case, she said.
"This case, of course, is just possession of a firearm unlawfully, which is itself serious, but it doesn't require the Crown to prove anything other than mere possession," Mathen said.
"It doesn't require the Crown to prove any harm was caused."
Dirk Derstine, a defence lawyer who will be arguing the case at the Supreme Court, said he anticipates most of the legal arguments will focus on the issue of cruel and unusual punishment, but the big picture will be about judicial discretion.
"That's very much something that many of the pieces of legislation that the Harper government has brought forward have been to restrict the discretion of judges," Derstine said.
"Many judges have fought back against that whole restriction. The restriction on judges by the legislature is really the fundamental nature of the battle that's going to be joined."
When the Court of Appeal for Ontario struck down the law as unconstitutional in November, the judges said they could conceive of a scenario in which people were sent to prison for three years for what would amount to a licence violation.
In that situation, there is a "cavernous disconnect" between the severity of such an offence and the severity of the sentence, the court ruled.