The federal commission that is studying how to legalize marijuana has recommended against setting limits for THC in the bloodstreams of drivers who use pot — for now.
“That’s the challenge right now — the science is not quite there,” committee chair Anne McLellan told reporters Tuesday in Ottawa.
The commission was looking at bringing in a per se system, which sets legal limits for levels of a substance in the blood for drivers, as we do with alcohol.
Britain and several U.S. states have set up a system that works this way.
“A particular challenge with a per se limit is that it implies that it is acceptable to consume up to the established limit,” the report says. “Yet there is currently no evidence to suggest there is an amount of THC that can be consumed such that it remains safe to drive.”
WATCH: Police across the country are getting ready for the legalization of marijuana, which is expected to happen in spring 2017. David Baxter spoke with police about how they plan on handling drivers influenced by marijuana, and got a first hand look at one of their current detection methods.
For drugs other than alcohol, Canada uses an effects-based enforcement system, which tries to measure a driver’s level of impairment by administering a complex series of tests. This approach is much more cumbersome than the one police take with alcohol-impaired drivers.
That system isn’t working, the commission conceded, in part because training specialist officers to recognize drug-impaired drivers is expensive and time-consuming. The courses are only taught in the U.S., and only in English.
“As a result, few officers have been trained, resulting in insufficient capacity to deal with the current rates of drug-impaired driving.”
Marijuana is the second-most common drug, after alcohol, found in the bodies of drivers who die in crashes.
Several other countries have set legal limits for THC found in the bloodstream of drivers, in micrograms, or millionths of a gram, of THC per litre of blood (µg/L). But the limits vary: Britain’s is 2µg/L, while Colorado and Washington have set 5µg/L.
The report makes it clear that the commission would like to have something similar in Canada, if a scientific basis could be found for it:
“Despite uncertainty with the current scientific evidence around a per se limit, establishing one would nevertheless be an important tool for deterring cannabis-impaired driving,” the report says.
“However, there was little agreement among experts on what that limit should be.”
The science is good enough to start enforcing per se limits for marijuana, argues Andrew Murie, CEO of Mothers Against Drunk Driving:
“We don’t know the precise number, but we know the range of the number. It’s probably between 5 and 10 (µg/L),” he says.
“Obviously we don’t have the decades of science that we had with alcohol, but we need that per se limit to be a guidance out there for people. Otherwise, especially with the limit set at 18, we’re going to have a lot more impaired driving and a lot more impaired driving crashes.”
The commission deferred to the Drugs and Driving Committee, a group of scientists who are advising the federal justice ministry on drug-impaired driving issues, McLellan said.
Roadside saliva testing for THC is also in its infancy, though experts say the technology has improved in the last few years.
In 2015, twice as many Ontario residents reported driving after using cannabis as did in 2010, according to the Centre for Addiction and Mental Health in Toronto (CAMH). The report shows that 5.6 per cent of men and 7.6 per cent of people between 18 and 29 admitted driving after using marijuana.