“Driving" is one of the required elements of a DUI offense. Driving requires "volitional movement of a vehicle." In everyday usage the phrase, "to drive a vehicle," is understood as requiring evidence of purposeful, actual movement of a vehicle.
Driving may be established by either direct or circumstantial evidence. Direct evidence of driving is where the law enforcement officer observed the individual driving in his presence. Circumstantial evidence of driving can occur where, for example, the driver is stopped by the side of the road, asleep at the wheel and intoxicated, with the engine running. The inference can be made that the only way the vehicle would have gotten to the side of the road was to have been driven there. As the person was by himself, it can also be inferred that he was the driver. Thus, circumstantial evidence is based on inferences which can be rebutted at trial.
California is not subject to a "care and control" statute and thus mere control of the vehicle is not sufficient to establish driving. Having care and control of a vehicle does not require actually driving it. It can apply to the occupation of the driver's seat, even where there are no keys. Walking towards the car with the keys could be sufficient. Some defenses are that the DUI arrestee was not impaired, or did not have care and control because they were not in the driver's seat, did not have the keys, etc. Having care and control depends on all circumstances.