There’s an easy way to comply with Canada’s new impaired driving law for marijuana: Don’t use marijuana at all. Considering that marijuana is now legal for recreational purposes in Canada, however, you ideally wouldn’t have to avoid marijuana completely in order to be legal to drive.
The effects of THC, the psychoactive component of cannabis, are only effective for a couple of hours. (The Canadian government says cautiously that it could be active for up to 12 hours.) The problem is that THC is stored in fat, and traces of it remain detectible for a month or more. Logically, people are not impaired after the few hours of intoxication, yet people still have THC in their systems long after the intoxication period is over.
That is why it’s important to test for impairment, not merely the presence of THC, when charging a driver with DUI. It would be easier to test for the mere presence of THC, but it wouldn’t be accurate — or just.
Nevertheless, Canada has adopted a per se standard. In other words, drivers are considered impaired if they test positive for 2 nanograms of TCH per milliliter of blood. Here are the new rules, which the Canadian government admits may be arbitrary:
• Testing positive for between 2 and 5 nanograms of THC per milliliter of blood within two hours of driving: $1,000 fine
• Testing positive for 5 or more nanograms per milliliter of blood within two hours of driving: $1,000 fine at minimum or, for repeat offenders, up to 10 years in jail
• Testing positive for a combination of alcohol and at least 2.5 nanograms of THC per milliliter of blood within two hours of driving: $1,000 fine at minimum or, for repeat offenders, up to 10 years in jail
Additionally, provinces have passed their own penalties for marijuana-impaired driving. Some of those include, for example, automatic driver’s license suspension and vehicle impoundment. Sometimes, these provincial penalties can be triggered by less THC than is allowed by the criminal code.
The determination of your THC level could be based on roadside tests, an oral fluid test called the Draeger DrugTest 5000, the observations of a drug recognition expert and, finally, a blood or urine test. For the most part, these tests do not measure actual intoxication but merely the presence of a certain amount of THC.
There are several problems with basing criminal charges on a specific THC level. A very important one is that drivers don’t know how to predict if they will be considered sober. Do you know how much cannabis you would have to consume to reach 2 nanograms per milliliter?