Canada's highest court has twice ruled that mandatory minimum sentences will "inevitably" and "unavoidably" result in miscarriages of justice.

The nine justices on Canada's Supreme Court, shown here in November, may soon be asked to rule on mandatory minimum sentencing requirements. Omnibus crime legislation currently before the Senate would toughen the mandatory sentencing for violent crimes and drug offences. (Fred Chartrand/Canadian Press)

But the Supreme Court of Canada has also cautioned the country's judiciary that it should only reluctantly override sentence guidelines set by politicians.

That's enough jurisprudence to feed the fears of critics of the Conservative government's "tough-on-crime" policies -- and also to bolster the arguments of those who say Parliament sets the law of the land, not the courts.

Mandatory minimum sentences are back in the news this week after an Ontario Superior Court judge refused to send a first-time gun offender to prison for three years.

Judge Anne Molloy ruled the mandatory minimum would be "fundamentally unfair, outrageous, abhorrent and intolerable" for the hapless Leroy Smickle of Toronto, and thus constituted "cruel and unusual punishment" under the Charter of Rights and Freedoms.

Smickle, who had a job and young family and no criminal record, was posing in his underwear in front of a computer with a loaded, illegal hand gun when police burst into the apartment looking for someone else.

Justice Minister Rob Nicholson suggested the Smickle judgment will be appealed in Ontario, and legal experts say the case is destined for the Supreme Court.

Supreme Court precedents

It wouldn't be the first time mandatory minimum sentences have come under the microscope of the Supremes.

'The Supreme Court of Canada has boxed themselves into a very dangerous corner'—Osgoode Hall law professor Alan Young

Twenty-five years ago, the top court issued a sharp rebuke to a mandatory minimum sentence of seven years for importing drugs.

While the case in question dealt with three-and-a-half ounces of cocaine, the court considered the hypothetical scenario of a teenager returning to Canada with a single marijuana joint.

The 1987 judgment reasoned that the minimum seven-year sentence in the Narcotics Act "covers many substances of varying degrees of danger, totally disregards the quantity imported and treats as irrelevant the reason for importing and the existence of any previous convictions."

The top court found that "arbitrary" seven-year drug minimums "will inevitably result, in some cases, in a legislatively ordained grossly disproportionate sentence."

The court struck down the law, saying it couldn't be assumed that prosecutors would use their discretion to avoid laying charges in cases that would violate the Charter.

"Everyone believed after that case that it would be very hard to sustain mandatory minimums in Canadian constitutional law," Alan Young, a professor of law at Toronto's Osgoode Hall, said in an interview Wednesday.

But since 1987 the top court has not found any other sentences that were "cruel and unusual punishment" and thus breached the Charter.

In 2000, the Supreme Court ruled in the case of a drunken, suicidal Nova Scotian with a sawed off shotgun who tripped and shot dead a friend in the bunk bed above him.

Marty Morrisey faced a four-year minimum for criminal negligence causing death with a firearm, but a lower court called the penalty excessive and gave him only three years.

An appeal court changed the sentence back to the mandatory four years, and the Supreme Court agreed.

"There will unavoidably be a case in which a four-year minimum sentence for this offence will be grossly disproportionate," the Supreme Court ruled in the Morrisey case.

But the top court said the "cruel and unusual punishment" section of the Charter only applies to a penalty "which is so excessive as to outrage our society's sense of decency."

Alan Young, shown here outside the Ontario Court of Appeal in Toronto in 2010, says the Supreme Court has Supreme Court of Canada has boxed themselves into a very dangerous corner with previous rulings on mandatory minimum sentences. (Aaron Vincent Elkaim/Canadian Press)

That's a high standard, said the judgment, and courts should be reluctant to "invalidate sentences crafted by legislators."

Another firearms manslaughter case in 2004 buttressed the Morrisey decision, with the top court ruling that judges cannot issue a "constitutional exemption" to a mandatory minimum if they feel the sentence is too harsh.

Such sentences, said the court, must either be found to be cruel and unusual -- and thus unconstitutional -- or be allowed to stand.

There's no middle ground.

More challenges expected

"The Supreme Court of Canada has boxed themselves into a very dangerous corner," Young, the Osgoode law professor, argues.

"They've made it a very dangerous zero-sum game. Either it's a minimum (sentence) or it's not, and you can't have any grey area where people who really don't deserve the minimum get the benefit of the judge's discretion."

Lawyers predict the latest Ontario Superior Court ruling will lead to other constitutional challenges of mandatory minimums, especially with a raft of new mandatory sentences for drug and sex crimes about to become law.

Young predicts the legal arguments against mandatory minimums will get "fine-tuned" in the couple of years it will take the Smickle case to get to the top court. That could change the landscape.

But in the meantime, said Young, he isn't sure the top court will strike them down.

"A wagering person would probably say right now they're more in favour of the minimums than they were in 1987."