If I was king for a day I wouldn't put breathalyzers in cars. I'd make the legal drinking limit .000. Everything would be so much simpler. I even thought that when I drove everywhere with a beer between my legs.
I think that changing the culture of drinking and driving, lowering the tolerance by society is what changes the amount of drunk driving. Just look at the acceptance of cigarette smoking in the US now, it has dropped drastically since I was a smoker in 1980. I see the same thing happening with drunk driving.