It's a ten year felony on the third offense in my state, I met a guy that later got sent to prison for years for it, a painter or something like that in a rural area, very nazi ish law enforcement up there, and that's lifetime count on the dui's.
As to the legal limits, .15 is not that high, legal limits used to be more like .12, but the feds refused highway sharing money with states if they didn't drop it to .08, as they were on their kick to make sure the police could find something to take down anyone that works for a living for one reason or another.
The feds also forced states to up their drinking ages to 21 refusing highway money to states that didn't up it from 18 or whatever. Louisiana was the last hold out and didn't do it until around 2001 or so, and their highways were shit because of it.
The feds don't have the authority to do most of what they do, and they got their foot in the door with money, because of their income taxes they've enough money to be able to use that to get the States, which by the constitution have a lot more power that the feds have now ursurped, to surrender it to them.
We are led to support the strong federal government because the south was all states rights to support slavery, and has since used cynical arguments when it served them for states rights, even as they repudiated them as often as not.
But the federal government is a monster that must be put back on it's leash, as could not be more clear. I digress though, no one thinks people should be driving drunk, I am just making the point, that .12 for generations was the standard, in some states. Different people have different tolerances due to genetic differences, and the limits are geared towards those with low tolerance to alcohol.
The larger problem is why we are completely reliant on vehicles, that we cannot even enjoy more than two drinks on the town and legally go home. There must be better ways, fuck cars.