Justice committee  I think that is a perception out there—

Justice committee  Yes, that cannabis is not a big problem when it comes to driving. It's not true. All the evidence suggests that it does increase crash risk, approximately doubles crash risk in cannabis users. It's far worse if you use it together with alcohol. I guess some of that perception may

Justice committee  It's just perception, yes.

Justice committee  Well, I think impairment sometimes impairs your ability to judge yourself, and it's often the case that people think that they're fine when they're not. So, no, that's not good advice.

Justice committee  Bob may be able to speak to this better than I can, but usually after you smoke it...approximately four hours longer after you take it orally, so up to eight hours, I think, after oral use. I'll turn it over to Bob, if he wants to....

Justice committee  Sure. I wouldn't say that Norway is using a very different number. They're using three, which is between two and five—

Justice committee  Well, yes, it's in that range. You're right, and we have to acknowledge that the research on when the crash risk starts to increase, exactly at what level, is not as well established as it is for alcohol. I think that most of the research would suggest that when you're above five

Justice committee  I think the per se limits have to be chosen carefully. I know, for example, that a heavy user could have a low level of THC, a nanogram per millilitre, that's detectable for a long time after they last use. You certainly don't want a per se level that's going to be catching every

Justice committee  I think drug recognition experts are a useful tool, but that has to do more with the per se limits. Let me answer the other part of your question first. In terms of recognition, these would be the front-line officers. The only way that a driver would come in contact with a drug

Justice committee  These were injured drivers seen in hospital after a crash, so there may be a different population. These are from about a decade ago. We compared toxicology testing done in hospital—alcohol levels—with their subsequent driver records. We found that of drivers with a BAC between .

Justice committee  Thank you for the opportunity to speak. I'm an associate professor at the University of British Columbia, with a research focus on impaired driving. I'm also an emergency physician at Vancouver General Hospital, which is one of Canada's largest trauma centres. I've worked at Van