Blood Alcohol Concentration (BAC) is a measure of the amount of alcohol in the bloodstream. Having a BAC of 0.10%, for example, means that there is one gram of alcohol per 1,000 milliliters (or one liter) of blood.
Because of the various ways alcohol can impair driving abilities, states have established strict legal limits on drivers’ blood alcohol concentration levels.
In California, the BAC limits are as follows:
BAC Legal Limit
Drivers age 21 or older
Truck drivers or anyone else driving a vehicle that requires a commercial driver’s license
Drivers with passengers for hire in the vehicle, as with taxis or ride share services
Drivers under age 21 or anyone who is on probation for driving under the influence (DUI)