DUI is a problem, and any human loss is painful, especially when avoidable. All that said, I feel like DUI is an overblown problem, in a way. 8 people dead per 1 million estimates incidents of DUI with a max. toll of 10k lives is not insignificant, and human loss is always bad. However, I disagree with your thesis. Curing cancer, raising the standard of living for the poor, and the death toll to obesity are all much more impactful things on society, though DUI is more 'senseless' and painful for victims.
I think limiting the need to drive is the only feasible option.
* You won't stop people from drinking in places where they can't sleep. Drinking at a bar costs 5-6x as much as drinking at someone's home, and yet people are constantly going out to be in a public drinking environment.
* Hopefully, we won't see mandated technology on vehicles requiring alcohol inspections for driving. Privacy, constitutional and technological issues all exist there. Yes, I know the devices exist, but they're clumsy, frustrating, and in the US are only used for people convicted of a 1st time DUI.
Solution: Incentivize people to walk or taxi home, or have a designated driver.
* By far the biggest immediate change that could be made: Make taxi services as cheap as possible. Stop limiting competition like Uber and the pedbikes in Austin from competition; while there are public safety concerns regarding drivers, I think the economic and safety benefits outweigh the risks. Cheap, responsive drivers = less drunk driving, period. ESPECIALLY in places like Texas, or most of the US, where public transit isn't ubiquitous.
* Allow mixed development and stop making suburban islands. If the hip bars are a three block walk from the houses and apartment complexes, fewer people will need to drive. Or, if you're making a suburban neighborhood, build the bar/drug store/grocer right into the town!
* The following thing is a dangerous and controversial thing to say, because it might imply that DUI is "okay": If you're going to drive after drinking, be honest with yourself. Don't say "I'm totally fine to drive". When you're exhausted on a trip, you don't just say you're fine and keep driving. You either pull over and sleep (get a cab) or you recognize your state and roll down the windows, turn on the radio, splash some water on your face, get a Red Bull, etc. If you are inebriated, say "I am drunk, don't speed, check my mirrors, watch out at all the intersections." That is a big cause of accidents, I'd be willing to bet. Whenever you see government propaganda about the dangers of DUI, it's the couple stumbling to the car, kissing each other, and not paying attention to driving. It's not good to drive when your body is impaired in ANY way, but the big problem is not recognizing your impaired state and focusing on the road.
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Postscript: DUI checkpoints are shit, and I don't care what the Supreme Court says. It's an invitation for the police to create probable cause and search your entire self and vehicle, your insurance, and if you piss them off, your cell phone. Even if you're sober, avoid them/fight them whenever possible.