Maybe it's time, though, to think outside the box on DWI instead of relying solely on criminal enforcement.
My better half observed recently that in London there's not nearly so much drunk driving as here because there's good public transit and a bar within walking distance in virtually every neighborhood. Examining data from Texas vs. the UK (pdf), our police make about one DWI arrest per 244 residents annually, while in England and Wales that figure is one out of 499. They also have FAR fewer alcohol-related traffic deaths compared to Texas (1,544 vs. 550 in 2006), though we have less than half their population.
By contrast, in Texas there is little public transportation (in Austin the bus route in my neighborhood quits running at midnight, even though bars close at 2 a.m.), but providing alternative transport would do a lot more to reduce drunk driving than further ramping up penalties.
What's more, most cities zone businesses that serve alcohol to non-residential areas, but then arrest drinkers who drive to and fro. How much sense does that make? Our laws have created a situation where you basically MUST drive to drink but then are subject to punishment for it.
Backing up this notion is a recent analysis showing DWI arrests are less common in "wet" Texas counties than "dry" ones. Why? IMO it's because people don't have to drive home from another county after they want to get a drink.
To believe the statistics from MADD, cops stop only a tiny fraction of those who drive drunk. So why not pursue complementary strategies? Investing in public transit and allowing bars zoned in or near residential neighborhoods would likely do more to solve this problem than further ramping up penalties or mandatory blood draws.