What is the legal limit for blood alcohol concentration (BAC) in most states for drivers over 21?

The legal limit for blood alcohol concentration (BAC) for drivers over 21 in most states is 0.08%. This standard is established to ensure safer driving conditions and to reduce the incidence of alcohol-related accidents. Drivers exceeding this limit are considered legally impaired, and law enforcement can cite them for DUI (driving under the influence).

This limit is supported by research that demonstrates that impairments in judgment, coordination, and reaction times begin to significantly affect driving abilities at this BAC level. The adoption of 0.08% as the national benchmark came with the National Highway Traffic Safety Administration's push for uniformity across states, which helped reinforce penalties for DUI offenses and promote public safety on the roads.