Q: What constitutes DUI/DAI in Pennsylvania? A: There are two definitions of DUI in Pennsylvania: 1) A person driving, operating or in physical control of a motor vehicle after imbibing a sufficent amount of alcohol such that the person is incapable of safely driving, operating or being in actual physical control of the motor vehicle. This is a subjective standard which is based upon many factors including driving behavior, field sobriety tests and physical signs of intoxication observed by police. 2) A person driving, operating or in actual physical control of a motor vehicle when alcohol concentration in the person's blood or breath is at least .08%. This is an objective standard which is based upon testing such as a blood test or an Intoxilyzer test.