I honestly don't understand why anyone should be opposed to this change, it is something that should have been done ages ago.

People with a blood alcohol level of something like 0.06 or 0.07 should *NOT* be on the road, they are badly impaired at that point!  This has been demonstrated time and time again that their ability to drive safely is badly reduced as compared to someone who is sober.

This isn't going to eliminate drunk driving by any means, but there are very good reasons why nearly every developed country in the world has already made this change.