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That’s why it’s so disappointing that patients and patient advocacy groups, including Canadians for Fair Access to Medical Marijuana, were denied an invitation to express their views at these sessions.

The proposed changes to driving impairment laws will introduce per se limits for cannabis, similar to how we identify those driving under the influence of alcohol. While this may make sense on the surface, the science simply isn’t there when it comes to correlating cannabis use and impairment.

Unlike blood alcohol concentration, which is scientifically linked to levels of impairment, matching impairment to levels of THC – the main psychoactive component in cannabis – is still widely debated.

Determining actual impairment of cognitive, psychomotor and other functions necessary to safely drive is not as simple as measuring the presence of THC in blood. Even more importantly, the effects of THC are different from person-to-person, and THC can remain detectable within a regular user’s blood for days, potentially weeks, after it was last consumed.

It should also be said that authorized medical users are expected to follow advice from health-care providers, including safe-use guidelines, such as waiting at least four-to-six hours after consumption before driving to help eliminate risk of impairment.

However, the government’s proposal, which would set a per se cut-off of 2ng/ml THC at the lower end, would mean patients would have to stop using their medication three-to-seven days (or more) before driving, which has nothing to do with impairment.