http://news.yahoo.com/canada-become-...204501904.html

We'll see how this works out. I think marijuana is safer than alcohol when it comes to driving but at least we have a way to measure alcohol. In California the BAC must be under .08 or else it's a DUI. How will Canada measure whether drivers have too much marijuana in their systems to drive safely? How do states like Colorado and Washington determine if a driver has had too much marijuana?