Just some thoughts in general on this subject:

There are what I call the "Journeyman drunk" who drinks at the same
club and knows the safest route home and all the hazards on it. If he
gets into an accident on this route, it will be someone elses fault.
(He is more likely to get into an accident on the way to work the next
day.) Before you respond to this, check this out with your police
experts - I did.
The greatest danger is the person who ties one on a couple times a
year. - wedding, alumni gathering and so on. Check this one, too.

For society, the best punishmentn for the drunk driver is to spend
weekends highway cleaning and nights in jail, working his regular job.
No welfare costs to society - but a really ****ed-off family being
educated and watching.

midlant