Experts are questioning whether a recent trend towards stiffer sentences for those who kill someone while drinking and driving are doing much to solve the problem.

Earlier this week, an Ontario judge acknowledged that recent high-profile decisions have established new precedents for the sorts of sentences drunk drivers can face if they cause a death while behind the wheel.

Justice Cary Boswell referenced several examples, including the 10-year-sentence handed down to Marco Muzzo after he pleaded guilty to killing three children and their grandfather while intoxicated.

He then continued the trend by sentencing 34-year-old Marcello Fracassi to six years behind bars for fatally striking a city worker from Alliston, Ont. while drunk.

Experts agree with Boswell's assessment that judges have been handing down harsher sentences, saying only British Columbia appears to be bucking the national trend.

But they also say the tougher sentences fail in their stated aims of deterring drunk drivers from getting behind the wheel.

Andrew Murie, Chief Executive of Mothers Against Drunk Driving Canada, said impaired motorists are more likely to be deterred by the possibility of getting caught, not the potential consequences of a hypothetical tragedy.

"It's not a deterrent," Murie said in a telephone interview. "It never has been, it never will. . . . There's other things that deter them, the penalties given out in court are not part of that."

There are few quantitative measures gauging what keeps people from getting behind the wheel after drinking, but Murie and others point to years worth of national statistics showing that impaired drivers are still frequently on Canada's roads.

The Traffic Injury Research Foundation (TIRF), which tracks fatalities based on police and coroner databases, said drunk driving has consistently accounted for nearly a third of deaths on Canada's roads for years.

In 2013, the last year for which data was available, TIRF said 480 people or nearly 28 per cent of all fatalities died as a result of impaired driving.

The number has come down from highs near 37 per cent in the mid 90s, but experts say fatalities are only part of the picture.

TIRF's 2016 Road Safety Monitor, which surveyed nearly 2,000 Canadians on their drinking and driving habits, found a spike in the number of people who admitted to getting behind the wheel within two hours of consuming alcohol.

The annual online poll found that nearly 22 per cent reported doing so, up five per cent from the year before. About 4.6 per cent said they believed they had driven while their blood alcohol content was over the legal limit, up modestly from the 2015 figure of 4.2 per cent.

The polling industry's professional body, the Marketing Research and Intelligence Association, says online surveys cannot be assigned a margin of error because they do not randomly sample the population.

TIRF Research Associate Steve Brown said the finding was disconcerting, adding it remains to be seen whether the 2016 result will evolve into a trend. Previous reports have noted spikes in individual years that have tapered off during the next poll.

Brown pointed to a number of proven deterrents that have emerged over the years, including graduated licensing programs with zero tolerance for alcohol on young drivers and administrative suspension powers accorded to the provinces.

But he shares Murie's views that stiff penalties are not a driving factor.

"There's going to be some people out there, it doesn't matter how strict the laws are, how tough the sentences are, there's this perception that they can get away with it," he said.

In Boswell's decision in the Fracassi case, he documented numerous court efforts to curb that perception over time.

In addition to Muzzo's case, he cited the 2008 sentence that sent former Toronto Maple Leafs captain Rob Ramage to prison for four years when his drunk driving resulted in the death of fellow NHL player Keith Magnuson.

He described the Muzzo sentence as a high watermark for penalties of its kind. It was matched in Saskatoon last year when Catherine Mackay was sentenced to a decade behind bars for killing a family of four after driving drunk.

Boswell said imposing sentences for impaired driving cases is difficult, since individual circumstances have to be considered.

In Fracassi's case, he said the young father was clearly deeply remorseful for driving home drunk in June 2014 and striking two Alliston city workers.

One was badly injured, while father of two Geoffrey Gaston suffered fatal injuries.

Boswell sentenced Fracassi to six years minus time served, saying long-standing public awareness of the gravity of drunk driving helps justify the trend towards tougher punishments.

"The reality is that the message about the dangers of impaired driving has been repeated, loudly and clearly, for decades now," he wrote in his decision. "For those who continue to ignore a message they have heard for most of their lives, moral blameworthiness is increased, just as societal tolerance is decreased."