Over the past 10 years, the standard or benchmark for determining whether a motorist is operating a vehicle under the influence of alcohol has been set at 0.08 blood alcohol concentration (BAC); although, this standard is not applicable to commercial and tractor trailer drivers who are subject to 0.04 BAC. The National Transportation Safety Board (NTSB) promulgated this benchmark.
The NTSB is a U.S. government investigative agency that was formed in 1967. Allegedly, the NTSB is an "independent group" that is primarily responsible for the investigation of transportation accidents including airplanes, boats, trains, pipelines and vehicles, among others. The NTSB is composed of five members that are nominated by the President of the United States (POTUS) and confirmed by the U.S. Senate for five-year terms. No more than three of the five members can be from the same political party. The most powerful weapon in the arsenal of the NTSB is its safety recommendation(s). The NTSB has advocated more than 13,000 recommendations in its timeline - most of these recommendations have been accepted and adopted - including the previous recommendation of 0.08 BAC for motorists.
States and other governmental entities adopt the recommendations of the NTSB because the NTSB is backed by the purse strings of the federal government. In other words, if any state rejects the new proposed 0.05 BAC benchmark for DUI drivers, then that state risks losing federal highway funding.