MANDEL: Drivers exceeding legal THC limit more likely to crash: Crown witness

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Drunk driving used to be considered the greatest threat to road safety.

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But driving while under the influence of drugs is catching up. Even before cannabis was legalized three years ago, a surprising Ontario study found that alcohol was present in 26% of drivers involved in fatal accidents, while THC — the primary psychoactive component of cannabis — was actually present in 27%.

“That was shocking, to say the least. We went back and checked that several times because it just didn’t seem possible,” said Dr. Doug Beirness, the expert in impaired driving who conducted the study. “Leading up to the legalization, the number of cannabis-related driver fatalities has increased substantially, and it now rivals alcohol as the substance of most concern to road safety.”

Beirness was testifying for the Crown in a Brampton courtroom against a bid to strike down Canada’s drug impairment law by lawyers for Brady Robertson, the 21-year-old Caledon man who ran a red light and broadsided an SUV carrying Karolina Ciasullo, 36, and her three little girls: Klara, 6, Lilianna, 3, and Mila, 1.

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Robertson has already pleaded guilty to four counts of dangerous driving causing death in the tragedy. But he has pleaded not guilty to four additional charges of impaired driving causing death, arguing the law that sets the legal THC limit at 5 ng/mL is unconstitutional.

It ultimately may mean little to the jeopardy Robertson faces — if he wins the Charter challenge, he likely still goes to prison on the dangerous driving convictions, but perhaps for a little less time than if he were also convicted on the impaired charges.

But what will it mean for other drug-impaired driving cases?

Defence toxicology expert, Dr. Jack Uetrecht, has testified that blood levels of THC don’t reflect the driver’s level of impairment. Unlike the over 80 measure for alcohol, a simple blood test for the more complicated THC molecule doesn’t correlate to being impaired, and chronic users can have residual levels of the drug in their system for up to a week.

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At the time of the crash, Robertson was speeding at more than 130 km/h while trying to outrun a Peel Regional Police officer who wanted to stop him for a missing front license plate. The Caledon driver had bought the blue Infiniti G35 12 days earlier but hadn’t registered the purchase and was using a rear plate that belonged to his aunt.

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A blood sample taken about 45 minutes after the triple fatal crash showed he had 40 ng/mL of THC — eight times the legal limit. He also had 21 ng/mL of Flubromazolam, an illegal street drug sedative similar to Ativan.

Ontario Superior Court Justice Sandra Caponecchia found Robertson guilty this week of impaired driving based on his being over the legal limit, but not on any evidence that showed his ability was impaired. “Depending on the timing, quantity consumed and his tolerance level, he may or may not have been experiencing the impairing effects of THC when he caused the collision at approximately 12:15 p.m.,” she said.

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Those convictions, though, are “subject to the outcome of the constitutional challenge” on the THC legal limit.

The Crown’s witness admitted that determining drug impairment in a driver is a challenge — there’s no simple breath test and it requires a lengthy, 12-step, hour-long evaluation by an accredited drug recognition expert.

Setting a legal limit for THC using a blood test is relatively new, Beirness explained, and while Canada’s limit of 5 ng/mL is widely used in other countries, some, such as Norway and Belgium, set it even lower.

It’s not an ideal measure of impairment, the expert conceded. “The one thing we do know from these studies,” Beirness said, “is people who have a blood cannabis level above 5 (ng/mL) have an increased risk of being involved in a crash and in particular, a fatal crash or serious injury crash.

“It’s not perfect but right now, it’s the best we can do.”

Final submissions on the Charter challenge are expected Nov. 8.

mmandel@postmedia.com

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