The way we "test" drunk/impaired drivers is patently retarded. We use bullshit arbitrary BAC tests that only tell us that some people would be impaired NOT that the actual driver was actually impaired.
I must believe that this is for a reason because it would be rediculously easy to come up with a better test that would impartially test if a driver was impaired regardless of why they were impaired. It could be done on the roadside and would be as quick and easy as current procedures. Hell, let me pick a handful of people from Anandtech and with a very small budget I guarantee we could have something up and running in a month.
Absent anything else, I have to believe that this is just another way to pick the pockets of their electorate.