Pennsylvania law for Driving Under the Influence requires that the person be operating a motor vehicle. Courts look to a number of factors to determine whether a person is "operating" or "in actual physical control of a motor vehicle." As stated, the courts do not employ a bright-line test, rather the courts look to the totality of the circumstances to determine whether the Commonwealth can prove operation of a vehicle.
The factors to be considered are: whether the defendant was in the driver's seat, keys were in the ignition, engine running or warm to touch, whether the car was legally parked, headlights on, parked in a location where alcohol is served, registration of vehicle, signs of visible intoxication, number of persons in the vehicle, and any other relevant factor.
The court views all of these factors and makes the determination as to whether the Commonwealth can prove operation. It is also important to note, the Commonwealth does not need to posses s direct evidence (meaning the officer does not need to actually see the defendant driving the vehicle in order to prove operation).