In order to charge someone with DUI, a police officer must have witnessed the defendant in “actual, physical control” of the vehicle. In other words, a police officer must see the defendant driving, or see the defendant in a position where he or she is capable of driving it.
If there was a traffic crash, officers may use investigation to determine whether the defendant was driving, but the arresting officer must personally investigate who was driving.
Using this defense depends on individual circumstances of the case. For example, were the keys in the ignition? Was the engine running? Was the vehicle parked or on the road? If you have been arrested for Driving Under the Influence, and you believe that you were not in actual physical control of the vehicle, the court may suppress the evidence or dismiss your case.