I've been involved with this for awhile, and I think this topic deserves it's own bogosity. This post isn't endorsing drinking and driving.
First off, to say MADD isn't a neo-prohibitionist organization is laughable. At one point, they tried to pass a law in my home state to have EVERY keg registered in a database and if your keg was found at a party with underage kids, you may be charged with a felony.
As for DUI laws themselves, it's ridiculous. At best, 60% of people can perform a field sobriety test WHEN SOBER. In addition, it's legally acceptable in my home state to have breathe tests that can be as much as .02 off. Just think about that then. A normal sized woman could have 2 beers at a bar and runs the risk of getting a DUI because of the machine.
And being 21 to drink, well, do I need to explain that?