Actually, in a brave experiment, we've actually decriminalized DUIs - because finding DUI requires getting a felony conviction including all the beyond-a-reasonable-doubt rules and all that. It's a complex enough conviction that DUI convictions are low.
Instead, what happens is there's a system of fines which are civil in nature, and beyond the first you get your car impounded instantly for a day, then a week, and a month. And all you have to do is blow 0.05.
Far lower requirements to lock someone up for a day and it apparently has an effect. Getting a criminal conviction takes time and courts, giving people fines and raising their insurance and impounding their cars is more of a bylaw style offense and can be instantly implemented.
DO it enough times and the insurance company mandates interlocks, which for some is a death sentence because their license is marked as having to drive an interlocked vehicle. Which means they are no longer able to drive a company vehicle (because no company wants to pay for an interlock installation), be it a car, truck, bus, whatever.
And we're not talking about cheap fines - $400 is cheap, but impound, towing and other fees bring that up to $1000 or so.
That may be the way to do it - then add get your license suspended enough times and you lose it. Go through Driver's Ed and take the tests all over again. (We have graduated licensing, so that's another year of having to be supervised followed by a couple of years of solo but under heavy restrictions including zero tolerance for impaired driving and only a single passenger, etc).
Getting convictions is hard, cycling through people is a lot easier. And having to get to work without a car gets the message across. And having your insurance rates go up because they're told of the incident to which they can apply their own actuarial tables and jack up your rates. That also means a checkpoint can easily detain 10+ people in one night with little to no paperwork since no formal charges will be laid.