I would answer that with a no. I think the fact that someone's a cannabis user is not a bar to driving, but when someone smokes cannabis, you usually will see impairment for two to three hours, sometimes stretching out to four or five. I think people who want to use marijuana, whether it's for therapeutic purposes or recreational, should understand they should not get behind the wheel for probably six to eight hours after use. With edibles, it's a whole different question because of the mechanics of how that's absorbed into the body and the effects can last for longer periods of time.
No, there's no safe level, just like with alcohol. The evidence is pretty clear that with the first drink, risk goes up with alcohol. The more you drink, the greater the risk. We place the burden on the legislatures, like the House of Commons, to determine how much risk is acceptable. The fact that you set a level, like we have 0.08% in the U.S. or 0.05%...if you want zero risk, you set the BAC level to zero. I think the same thing is going to be true about marijuana.