One thing I've always found interesting/perplexing about the United States is that every state has a different DUI level. To me it's interesting what each state considers too high of a BAC to drive with.
In Japan there is no debate. If you have a drink in Japan you are not allowed to drive. Anything over basically a 0.0% BAC is illegal. On top of that, if a restaurant or bar serves someone a drink they are responsible to make sure that person does not drive. If the person drives and gets caught, the bar/restaurant will get a huge fine. Even harsher, anyone who knowingly lets someone drive after drinking is also held responsible if the person causes an accident.
These laws may seem harsh, but I think the Japanese are on to something. Every year in America thousand of people die from DUI related accidents. How much lower would that number be if there was a zero tolerance policy?