In my opinion .08 is too low. I know, I know...drunk drivers are worse than Hitler and no one wants to seem sympathetic to them at all. Seriously though, the penalties for being at .09 are way out of whack compared to the danger someone with a BAC of .09 poses. I think a .09 DUI should result in a fine similar to speeding and the driver should get to drive home. No kidding. At about .12 I think people should be arrested, get the $1000plus in fines, get dropped by their insurance company, lose their license for 6 months, etc. like what happens now for someone who in most cases you probably wouldn't be able to tell even had a drink.
So based on that overreaction I don't want pot heads to face DUI charges because they smoked a joint two days ago, either. I think it should come down to the filed sobriety test and the manner in which they were observed driving.
Whereas I get that, scientifically .. I'd prefer a no-tolerance driving law. Just about everyone that goes out and has a couple drinks thinks they're below and has one more .. too easy to actually have too much. It's a much simpler law to say NONE.