The NTSB is recommending that States lower blood-alcohol-content (BAC) to 0.05. The nationwide standard is currently 0.08. The US is one of the few countries to have 0.08 limit:
The United States, Canada and Iraq are among a small handful of countries that have set the BAC level at .08. Most countries in Europe, including Russia, most of South America and Australia, have set BAC levels at .05 to constitute drunken driving.
When Australia dropped its BAC level from .08 to .05, provinces reported a 5-18 percent drop in traffic fatalities.
Australia enacted the 0.05 law in 1991. The interesting thing is that a lot of the reduction in fatalities was from drivers having BAC in the greater than .08 range:
A similar reduction was found in roadside random breath tests:
It should be noted that the law did not change at all for drivers with BAC .08 and higher. It was only for .05-.o8 levels that the law changed. The rationale from the NTSB is that there are biological reasons for reducing the BAC level to .05, but it is possible there are other factors that explain the reduction in fatalities.