How will Canada crack down on marijuana-impaired drivers?

Law enforcement agencies should prepare for an influx of drug-impaireddrivers before marijuana is legalized in Canada, says an American state trooper.

When Colorado legalized marijuana in 2014, police weren't prepared to crack down on those who lightup before getting behind the wheel, saidLt.-Col. Kevin Eldridge.

You have to think about how you're going to deal with this increase of a drug in the society, and how you keep people from driving under the influence.- Lt.-Col. KevinEldridge

"Most traffic agencies in Canada are very focused on driving down traffic fatalities, and this is a cog in the wheel,"said Eldridge, who sharedlessons on enforcement with traffic safety experts from across the country during Monday'sInternational Conference on Urban Traffic Safetyin Edmonton.

"You have to think about how you're going to deal with this increase of a drug in the society, and how you keep people from driving under the influence."

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The federal government has promised to begin the process of legalizing recreational cannabis in the spring of 2017. The Liberals haveprovided no furtherdetails, however, on what the legislation might look like, leaving the question of road safety unanswered.

Eldridge saidCanadian policeagencies will be left scrambling if theyfail to develop new officer training and enforcement policies well in advance of legalization.

"There were several different policies we had to change," he said. "When they legalized, everyone focused on this one aspect, smoking marijuana is legal. But officer hiring, employment, and evidence there were many different aspects that we really didn't think about as much as we should have before implementation."

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Drug-impaireddrivers hard to detect

Detecting stoners behind the wheel remains one of the biggest challenges for Colorado police officers, Eldridge said.

The Colorado State Patrol is usingmarijuana DUI devices as part of a three-year pilot program.

It impacts your ability to focus, to judge, to perceive, depth perception, control, all of that is under the influence.- Lt.-Col. KevinEldridge

More than 125 troopers have been equipped with one of five types of an oral fluid tester that samples a driver's saliva for the presence of drugs, including marijuana. But the devices have not been officially approved, and it will be two more years before the pilot is completed.

"It impacts and impairs driving," Eldridge said of marijuana. "Whether it's any drug, it impacts your ability to focus, to judge, to perceive, depth perception, control, all of that is under the influence.But we're still trying to really get a handle on what that looks like with marijuana."

Canada is exploring the use of similar DUI devices,but they need to be extensively tested in the field, and legislative changes will need to be made before they can be adopted.

How much is too much?

Just how much marijuana intoxication if anywill legally be allowed for Canadian drivers remains unclear.

In Colorado, drivers with five nanograms of active tetrahydrocannabinol (THC) in their blood can be prosecuted for driving under the influence. But blood tests areneeded to enforce that limit.

No matter what level of THC, officers in Colorado can still make arrests based on their judgment. Eldridge saidthe effects of THC on individual users can be unpredictable, and even minute amounts can make some drivers dangerous.

"It's illegal in Colorado to drive a vehicle while impaired by anything, alcohol or drugs, and the drugs can be legal drugs, over-the-counter drugs or illegal drugs," said Eldridge.

"There's not really a quantifiable amount for marijuana right now, because the drug affects people so much differently than alcohol there's just not that level of study for marijuana yet."

Trend difficult to track

In Colorado, about 10 per cent of drivers involved in fatal accidents in 2010 tested positive for the drug. By 2014, just over a year after recreational sales were legalized, that number had nearly doubled to 19 per cent.

DUI summonses involving marijuana (either alone or in combination with other drugs, usually alcohol) fell one per cent between 2014 and 2015.

But Eldridge saidthe number of drug-impaireddrivers, and how much danger they pose on the state's roads, has so far been difficult to track. The Colorado State Patrol only began collecting information about specific drugs involved in drivingundertheinfluence cases in 2014, Eldridge said.

Before then, policerecords didn't single out different types of drugs in data collection for crime statistics.

"When you arrestedsomeone for driving under the influence, it's either driving under the influence of alcohol or driving under the influence of drugs. Nobody really knows how many you have, because no one separated those prior to the legalization of marijuana," said Eldridge."They were all lumped together."