American adults are often quite cautious about keeping their blood alcohol content (BAC) levels under control before attempting to operate motor vehicles. Failure to keep one’s BAC below the legal limit of 0.08 percent can lead to drunk driving charges, so it is imperative that any adult planning to drive after drinking waits long enough for the alcohol in his or her body to metabolize below that limit before getting behind the wheel of a car or truck.
However, it is possible for drunk driving charges to result even when one’s BAC is below the legal limit of 0.08 percent. The general threshold of 0.08 percent BAC only applies when an adult driver has no prior convictions related to driving under the influence (DUI), is legally old enough to drink and does not seem impaired at BAC levels below 0.08 percent.
When drivers are younger than 21 years of age, any alcohol detected in their system during a traffic stop can result in a DUI charge. This zero tolerance policy is enforced in order to discourage underage drinking and to hold young people accountable for choosing to drink any amount before attempting to operate a vehicle. Zero tolerance policies may also apply to persons formerly convicted of DUI offenses. However, thresholds for repeat offenders may vary from state to state.
In addition, it is illegal to drive while impaired, no matter how little of a given drug or alcoholic beverage you have in your system. You may therefore be convicted of a DUI charge if you are visibly impaired while driving, even if the amount of alcohol or prescription drugs in your system does not exceed generally accepted BAC limits.
Source: Findlaw Blotter, “BAC Below 0.08%? It Can Still Be a DUI,” Aditi Mukherji, Aug. 22, 2013