How much cannabis could you smoke and stay under the proposed legal limit for driving? The answer may be zero
Last month, at a city council meeting in Kelowna, B.C., the ranking RCMP officer was giving his quarterly update on policing when a councillor posed a question about marijuana. “I know that when I go out for the evening, I can have a beer, and I know the alcohol content in that beer,” said Coun. Ryan Donn. “I know that one would be a good limit for myself to have before getting in a car and driving.
“When I think about cannabis, I really, truly have no idea,” he went on.
“Can it be used an hour before, three hours before? We’re about to go into a world that I don’t know anything about, to be honest with you. How long does it stay in the system? … I know that I don’t have the answers if people ask me on the street.”
RCMP Supt. Brent Mundle had little to offer in response, beyond saying public education is generally behind on this and that federal rules are still under discussion. “I think there’s going to be a significant learning process for everyone, especially those people that are using cannabis and then operating vehicles, as to what is a safe limit,” he said.
Newly-released internal government research indicates this confusion is widespread. A Public Safety Canada survey conducted by EKOS Research Associates last fall found that although most people understand it’s illegal to drive when impaired by drugs, 43 per cent of Canadians don’t know how long to wait to drive after consuming pot, and one in six felt three hours was long enough — a significant underestimate.
Among marijuana users in the survey, 28 per cent had reported driving under the influence at some point, and among that group, 25 per cent felt it was less dangerous than driving drunk and 17 per cent felt there was no risk to their driving. This follows a Health Canada survey released last year that found 39 per cent of marijuana users had at some point driven within two hours of consuming cannabis, and only half of pot users felt the drug affected their driving ability.
With marijuana legalization looming, it’s a question about to become incredibly important: Smoking a joint will be legal, but how much can you smoke and drive without breaking Canada’s increasingly severe impaired driving laws? And those laws are about to get even tougher, with federal legislation working its way through Parliament to coincide with legalization. (The legislation could still be amended before passing.)
But the reality is that nobody can say for certain how much cannabis makes you too impaired to operate a vehicle. In the vacuum of such science, the federal government is proposing an approach that would mean even a couple tokes on a joint could put you over the new legal limit, if only briefly. The country may be in for a rude awakening.
Changes in the works
As any police officer will tell you, this is not a new problem. It’s already illegal to drive when impaired by any drug, including legal prescription drugs. Police already use field sobriety tests on drivers to detect impairment (for example, walking in a straight line). The rate of police-reported drug-impaired driving has been rising for years.
But Bill C-46, the legislation now being hotly debated in the Senate, would introduce two major changes on this issue.
One is the addition of roadside screening devices that allow police to test saliva for multiple drugs, including THC (the primary psychoactive in cannabis). The justice department has commissioned testing of devices and is expected to approve some for use later this spring.
But the most significant change is the creation of “per se” limits for THC levels in the blood. This is essentially a legal shortcut that allows police to lay an impaired driving charge based on a driver’s blood THC level, without having to further prove impairment.
Police already use per se limits for alcohol impairment. But breathalyzers and blood alcohol concentration have been proven to have a close, predictable link to impairment. The same is simply not true of saliva testing and blood THC levels, and this is where things get tricky.
Will Bill C-46 in its current form mean non-impaired drivers are nailed with criminal charges? The government points to two main safeguards in its defence.
First, police must reasonably suspect a driver is impaired before ordering further testing for drugs. This could include, for example, smelling marijuana or observing slurred speech and bloodshot eyes. (Controversially, Bill C-46 removes this requirement when it comes to breathalyzers, precisely because alcohol testing is much more reliable.)
Once an officer has reasonable suspicion, a saliva test or a field sobriety test could be ordered. Based on that evidence, a driver could be brought back to the police station for a blood test, an examination by a drug recognition expert, or both. The new per se limits on THC would allow police to immediately lay charges based on the blood test results.
But toxicologists point out that blood THC levels do not necessarily mean impairment. Even a small amount of cannabis can cause your THC level to spike before dropping and levelling out. THC is also fat-soluble, meaning it can show up in the blood for days after consumption.
The government’s second safeguard, then, is the creation of a “low blood drug concentration offence” that comes with a fine of up to $1,000, but otherwise exempts drivers from the harsh minimum sentencing for impaired driving convictions. A justice official told senators this category is meant to “send the message that you don’t mix marijuana and driving.”
The government proposes the lower-level offence would apply to drivers who test between two and five nanograms of THC per millilitre of blood. Drivers who test above five ng, or who test above 2.5 ng combined with a blood alcohol concentration above 50 milligrams per 100 mL, would receive the existing Criminal Code impaired driving penalties that mandate jail time for repeat convictions.
Could someone stay under these proposed limits while using cannabis? Trying would be risky.
“If you look at the concentration of THC in the blood from the experimental studies, there is no amount of cannabis that you can smoke that will not at some point put you over the legal limit,” said Doug Beirness, a Canadian Centre on Substance Abuse researcher who serves on the expert committee advising the government on the issue.
“One puff? One hit? Is that going to do it? Well, I don’t know,” he said. “From what I can see from the blood concentration curves, it will still get you over the two or five (ng). Maybe only for a brief period of time, but it will get you over that level.”
As for how long it takes to leave your system, there’s no catch-all rule. It depends on how much you take, your body size, your gender, your history of use. If you aren’t showing signs of impairment, theoretically you should be fine. But the saliva-testing machines will stop detecting it after six to eight hours, so that’s the only safe answer.
The public conversation
Everyone agrees public education is crucial. The 2018 federal budget promised $62.5 million over five years, and Public Safety Canada already has an advertising campaign on the dangers of driving high.
But the government has its work cut out for it. Surveys have repeatedly shown that many pot users understate the risks when it comes to driving. The Public Safety survey, which was conducted to help inform its advertising, showed that just 42 per cent of Canadians feel there’s adequate information available to help them make informed decisions on driving while under the influence of drugs.
Many complicating factors remain. How will medical marijuana cases play out in court? How will edibles (to be legalized within a year) affect the tests? What additional penalties will provinces bring in? Will police have the resources to enforce these laws effectively? Senators warn they may significantly amend Bill C-46; will the government stand its ground?
Regardless, Beirness said Canadians will need to change their way of thinking when it comes to cannabis. Attempting to smoke and stay under the limit could bring criminal sanctions with life-long consequences.
“One of the worst things that we did with alcohol many, many years ago was set a limit, because it gets people to ask the wrong question,” he said. “It’s ‘how much can I have and still drive?’ It leads to a guessing game, and people guess wrong.”
Donn, the Kelowna councillor, said in an interview that the zero tolerance approach for pot comes as news to him. And based on the comments on his Facebook page following the council meeting, he said it’s clear many constituents have the same confusion.
“People assume that legality means ‘I get to live my life and smoke weed in my recreational time’,” he said.
“We haven’t had the public conversation on what is acceptable and not acceptable with a legal substance. It takes time for this stuff to seep into the public and have a conversation.”