Section 23152(a) is used when DUI involves drugs, when there was no BAC testing performed or when BAC is below .08, but the government wants to prosecute the person anyway. Drivers whose BAC does not exceed the presumptive BAC limits can still be convicted of DUI if other evidence shows their abilities were impaired.

Section 23152(b) is called the “per se” law as it clearly indicates that driving with a blood alcohol level above 0.08* violates the law. Drivers who exceed the BAC (Blood Alcohol Content) limit are presumed to have been under the influence of alcohol when driving, meaning that their faculties for driving were impaired. This quite frankly, may not be the case as some people build a tolerance for alcohol. They may consume fairly large amounts and still function fairly competently.