Let me just add a few minor points.
One is to add flexibility to the criminal justice system, because right now there's inflexibility, which leads to an insistence on trials in drunk driving cases and an insistence on fighting these cases tooth and nail to the very end. If there were a measure of flexibility in terms of punishment, matters would be different.
Second, let's not ever forget the role of public education, which certainly goes a long way towards teaching people a better way of living and avoiding this type of offence. I agree that the risk of getting caught deters people, but the same is accomplished by having a RIDE program alone on every street corner. If you think you're going to get stopped by RIDE or a police officer—leave aside the mandatory breath sample—you'll think twice about driving drunk.