Drunk driving is a serious offense.
But it’s not criminal. Not even a felony, is it?
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It is criminal/felonious depending on the circumstances.
http://dui.findlaw.com/articles/1448.html
Actually a DUI conviction is always criminal.
http://criminal.findlaw.com/crimes/criminal-overview/felony-vs-misdemeanor.html
Recognize that my comment had to do with the scale of punishment (presumably indicative of seriousness) -- not with your individual perception of the crime.