Can I just comment as well? In B.C., the province that I'm from, in 2010 they implemented what's called the IRP, the immediate roadside prohibition. If an officer suspects that you may be driving impaired, that officer could pull you over and make you blow into a Breathalyzer to see if you are in the warn range, at 0.05, or if you are impaired, at 0.08.
It's been very effective. Fatalities have dropped by 43%. However, in saying that, in the past six years in B.C. alone, they have given out 170,155 immediate roadside prohibitions, administrative driving prohibitions, and 24-hour suspensions. That's only the ones that they have caught. They said that for every one they catch, they assume a hundred more get away. That's an awful lot of impaired drivers.