Canada's proposed overhaul of federal impaired driving rules could unfairly criminalize medical cannabis users, according to an open letter to Ottawa signed by more than 50 criminal defence lawyers.
The letter, which warns that medical marijuana users could be unfairly punished under the proposed system, underscores the challenges to preventing high driving. Experts are divided on just how much THC – the principal psychoactive compound of cannabis – would make someone impaired, and the government is still developing a reliable way to conduct a roadside test.
As the federal government and the provinces rush to meet the deadline for legalizing the drug by next summer, a key concern has been settling on what is known as a per se limit, which specifies how much of the drug has to be in a driver's system to constitute a criminal offence.
Ottawa has decided that people with at least two but less than five nanograms of THC a millilitre of blood detected within two hours of driving would be subject only to a fine, to a maximum of $1,000. Those with at least five nanograms would be treated more seriously. In the United States, both Colorado and Washington State have adopted a single drug-impaired driving offence at five nanograms.
Critics say such a two-tiered system of offences, similar to how drunk drivers are treated in some provinces, does not work for cannabis because the drug affects each person differently and there is no agreed-upon level of intoxication, as there is with blood-alcohol levels.
The letter sent Monday to the federal Department of Justice calls on Ottawa to do away with the two-nanogram threshold. The statement argues that limit could unfairly penalize some 200,000 licensed medical users whose regular consumption can lead to them having that level of THC in their blood days after last using the drug.
"The government has asserted that the 5 ng/ml threshold for a hybrid offence 'could be associated with some impairment,' but has also conceded that the 2 ng/ml threshold is 'not directly' tied to impairment and rather reflects 'a precautionary or crime prevention approach,'" says the letter circulated by Toronto-based articling student Harrison Jordan. "We cannot in good conscience support the implementation of an offence that carries with it a negligible nexus to criminality."
Kyla Lee, a Vancouver-based lawyer who signed the letter and who represents drug-impaired drivers, said lawyers are already preparing to file constitutional challenges when the legislation is passed next year.
"At this point, I think it's inevitable that this law is going to pass," said Ms. Lee, who was invited by the House justice committee to present on this matter this fall. "Now it's for us to make sure that the courts sort it."
Ms. Lee said Ottawa would be better off crafting rules that hinge upon an officer assessing a cannabis user's ability to drive via field sobriety tests, not saliva-based THC tests.
Jeff Brubacher, an emergency-room doctor at Vancouver General Hospital and a clinical toxicologist, said this approach may be problematic, as many front-line officers have trouble determining when people are high behind the wheel.
About 4 per cent of drivers who had been in a crash had THC levels higher than two nanograms, according to a study by Dr. Brubacher analyzing recent data from patients who ended up in four of British Columbia's busiest emergency rooms. Yet police only suspected drug use in 8.5 per cent of those drivers caught with between two and five nanograms of THC, according to Dr. Brubacher.
"When THC levels got higher, it didn't get any better," he said. "Police have a really hard time detecting drivers who are using drugs."
He said such per se THC limits give police a tool that is pretty efficient.
Still, the Canadian Association of Chiefs of Police has stated in its submission to the federal standing committee on justice and human rights that oral fluid screening devices "are not determinative of blood drug levels or impairment."