Many people can drive find after having a couple of drinks. The limit we have right now is good enough. In fact, I think the limit now is even a little bit low and could be raised to .10 percent. I am against drunk driving, but buzzed driving definitely isn't drunk driving.
There are already plenty of tight alcohol laws regarding drivers, and yet many DUI offenders are repeat offenders. The issue is not the limit being tight enough, but offenders getting off easy and going right back at it. Fix the courts, not the legislation. In fact, that level is so low it is too easy to get false hits.
I don't care where you set the DUI BAC level at, we will always have people who are foolish enough and selfish enough to get in their vehicle and drive after drinking. Most states are at 0.08% which is more than likely sufficient since many people can function fine at that number. Assuming the problem will go away by lowering that one little number is a false assumption.
The DUI limit changes from state to state. Some states have added a DWAI which is a much lower limit. This is at the discretion of the states since most states conduct their own traffic laws. The blood/alcohol Content being lowered to 0.05% would not drastically impact anything. This would just change some training. Most DUI's are significantly over the legal limit anyhow.