The outrage on social media was palpable. "Murderer," some said. "Rot in hell," others cried. An online petition with more than 6,000 signatures demands a life sentence. On Twitter and Facebook, strangers demanded much worse.

The target of this wrath is Marco Muzzo, 29, who has been in jail since his Jeep SUV plowed into a minivan late one afternoon in September at a quiet intersection of two country roads in Vaughan, killing three young children and their grandfather, and injuring their grandmother and great-grandmother.

Mr. Muzzo faces 18 criminal charges, including four of impaired driving causing death. Next week, his case is back in court in Newmarket. He is to appear on a video screen from jail.

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His current infamy can also be blamed on the fact that he is the grandson and namesake of a billionaire developer, the late Marco Muzzo, whose companies helped build the Toronto area's sprawling suburbs. Engaged to be married, the younger Mr. Muzzo, according to a source, was returning home from a weekend bachelor party after being dropped off from a private jet. He has retained Brian Greenspan, one of the city's top defence lawyers.

Jennifer Neville-Lake, the mother of the three children, who were 9, 5 and 2 when they were killed, has called for the maximum sentence if Mr. Muzzo is convicted, and has urged the public to push for life sentences for other drunk drivers who kill: "If enough people ask for the harshest sentence, it will be considered."

But legal observers believe a life sentence, which on paper is the maximum for a charge of impaired driving causing death, is extremely unlikely and would be meted out only in an extreme case for a repeat offender. A guilty verdict in a recent Toronto drunk-driving case that involved two deaths resulted in a five-year sentence.

But the length of the sentence may be the wrong metric for measuring whether we are winning the battle to keep drunk drivers off the roads. Deaths attributed to drunk driving fell in the 1980s as new laws and public-awareness campaigns kicked in, but those declines have largely stalled since the turn of the century.

And while Canadians drink less alcohol per capita than citizens of many comparable countries, one study of 13 similar nations put Canada second only to the United States for annual drunk-driving deaths. Groups that campaign against drunk-driving say this is because of laws that make it more difficult for police to press charges against drunk drivers.

Unlike Mr. Muzzo, most drivers in Canada who allegedly have alcohol in their blood and cause a serious crash never face an impaired driving charge, Mothers Against Drunk Driving Canada says.

That is largely because many end up in hospital.

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"Getting to the hospital is a get-out-of-jail-free card," says Robert Solomon, a law professor at the University of Western Ontario who is also the national director of legal policy for MADD Canada.

According to MADD's estimates, Canada had more than 1,000 fatalities from alcohol-related crashes in 2010, but only 125 charges and 48 convictions for impaired driving causing death (as many as half of the people killed in these accidents may have been the impaired drivers and some crashes involved multiple victims). A 2004 study from British Columbia of hospital data found that only 11 per cent of hospitalized drivers who were involved in crashes and had blood-alcohol levels above the legal maximum of 0.08 per cent were convicted of any criminal impaired-driving charge.

The reason, Prof. Solomon says, is that police often cannot get samples from these drivers at the roadside, and the procedure to obtain judicial warrants to seize blood samples or test results at the hospital is "exceedingly technical and complex" and "narrowly interpreted" by the courts. In general terms, to secure a warrant or demand a breath sample, police need to show they have reasonable grounds to suspect a driver was impaired, such as detecting the smell of alcohol.

"Our federal law does not give the police sufficient power to effectively enforce the law," he said. "We don't need tougher laws. We need smart, effective laws. We need laws that prevent these deaths and injuries from occurring."

(This was not an issue in the case of Mr. Muzzo, who was uninjured in the crash. According to police sources quoted in media reports shortly after the crash, he took two breath tests and blew twice the legal alcohol limit.)

Countries where police have more sweeping powers to demand breath and blood samples have much better scorecards on convicting drunk drivers: In Sweden, Prof. Solomon said, 85 per cent of hospitalized drunk drivers were convicted of impaired driving. In the Australian state of Victoria, the conviction rate was more than 90 per cent.

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Toronto Police Constable Clinton Stibbe insists police here can get the blood samples they need to prosecute drunk drivers, but must follow the rules to ensure the Charter rights of the accused are not violated.

An officer usually accompanies a suspected drunk driver to hospital, he said, and brings a breath tester along if one could not be performed by the roadside. He said police routinely draw up warrants to get blood samples and other medical documents for hospitalized suspects who refuse or cannot do a breath test.

"We have the ability to go the hospitals. We have the ability to write the warrants, I mean this is what we do on a regular basis," Constable Stibbe said. "To say that we can't get that information is inaccurate."

He suggested that MADD's statistics, which do not include other criminal charges that might be laid in the crashes, such as aggressive driving, may overstate the extent to which drivers in serious accidents evade justice.

The federal government has been studying possible changes to drunk-driving laws for years. Bill C-73, hastily introduced by the Conservatives in the dying days of the last Parliament, proposed allowing mere involvement in a crash that causes death or bodily harm to be reasonable grounds for police to demand a breath test or a blood sample, strengthening the prosecution's hand.

The bill, which died on the order paper, would have also brought in a six-year mandatory minimum sentence for impaired driving causing death.

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While it was applauded by some families of crash victims, MADD says the minimum would likely have been struck down in a Charter challenge because it would have been double the average three-year sentence meted out now.

Research shows longer sentences are not a deterrent, Prof. Solomon said, arguing that Canada would be wiser to follow other countries and bring in random roadside breath testing, which has been shown to make people think twice about driving drunk.

Canadian police at a roadside check must have reasonable grounds to demand a breath test. In many countries, including Australia, officers can choose drivers at random and order a breath test. The Canadian Bar Association has warned that such a system would bog the courts down with Charter challenges. But Prof. Solomon said reducing the legal limit to 0.05 from 0.08 and bringing in random testing could cause drunk-driving deaths to plunge by 20 to 30 per cent.

Still, many victims' families continue to demand longer prison terms.

Andrew Murie, the chief executive officer of MADD Canada, said sentences have increased dramatically since he started with the organization 20 years ago, going from 18 months to an average of three years and often more than four. House arrest and conditional sentences were done away with in 2008. Still, the organization supports longer jail terms.

In a recent Toronto case involving a first offence, Sabastian Prosa was sentenced to five years for impaired driving causing death after a 2012 wrong-way crash on Highway 427 killed two people. Crown prosecutors had asked for eight years. Mr. Murie said MADD supporters felt the sentence was not enough – but almost any jail term seems too short to families torn apart by the loss of a loved one.

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"They go and look at the maximum, which is life, and they look at their family member, who's gone for life, and they expect a really high penalty," Mr. Murie said. "And they are very disillusioned and disappointed with the criminal justice system. … But there's no sense in giving a sentence that is going to be appealed and struck down."

Whatever the results for Mr. Muzzo in court, a Toronto-area couple lost their three children in the wreck that Sunday afternoon. Ms. Neville-Lake learned of the crash when she saw the demolished minivan on television.

"It's been very surreal. Like a dream," she told a reporter from TV station CP24, standing in her driveway the day after the crash. "You can catch glimpses of the children. You hear them. It just doesn't seem quite real yet."

Alcohol-related traffic deaths per 100,000 population, 2008

1. United States 4.53

2. Canada 3.17

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3. Ireland 2.84

4. New Zealand 2.78

5. Australia 2

6. France 1.95

7. Finland 1.81

8. Denmark 1.69

9. Britain 0.70

10. Germany 0.63

11. Sweden 0.40

12. Japan 0.34

13. The Netherlands 0.15

Source: MADD Canada

Editor's Note: An earlier version of this story said Mr. Muzzo was returning home from a weekend bachelor party in Las Vegas. It is not known where he was coming from at this time. This version has been corrected.