Also, to get to .16 if you are a 180 pound man would take 7 drinks in the first hour.
http://www.faslink.org/bal.htm
If you happen to be a scrawny little 140 pound dude, it would take 5 drinks in the first hour.
I get the .16- basically they are saying if you made a slight error in judgement and drove at .09- still illeagal but we aren't going to fry you. If you ever drive at .16 you need some serious help.