The .08 national blood alcohol legal limit can't be the magic number for everyone. There are some people who can be at .12 and drive excellently. There's also people who can't handle driving at .04. How to remedy this problem of averages? A drunk driving test. You drink as much as you want, and you take a complicated driving test. If you pass, they give you the breathalyser on the spot, and if it rings a .10, that's your new legal limit.