There's under the influence of and there's incapable by reason of and there over the limit...And different places draw different limits.

But if it's danger to yourself that's a factor, that should apply to pedestrians to. And people fixing a snack in a kitchen full of lethal equipment.(That would really threaten potheads!)

And if your blood sugar is low because you missed lunch, or you haven't had enough sleep, that impairs you too...I think a zero-tolerance all-or-nothing approach tends to run into a few problems. And that doesn't mean I don't think coming down heavy on people driving irresponsibly for whatever reason isn't a good idea.