Inherently, every DUI statute prohibits a person from driving or being in actual physical control of a vehicle. The problem arises where the law fails to provide the type of devices that it intends to be covered or fails to define the terms that are used in the statute. Ultimately, because the statute is not specific enough, the final determination is left up to the courts.

Most DUI statutes use the terms "vehicle" and "motor vehicle". The Uniform Vehicle Code uses the term "vehicle". Obviously, the term “vehicle” is broader in scope than motor vehicle. For example, one court rejected an argument that the defendant’s automobile was not a vehicle since it was stuck in the mud it did not have the ability or capacity to transport. Some statutes define a vehicle as a device to transport people; hence a road roller was not considered a vehicle.

Still, courts have determined that most devices with a motor satisfy the “vehicle” definition. Golf carts and farm tractors have been held to be vehicles even though they do not strictly transport people. On the other hand, bicycles, horses and snowmobiles have been held to be vehicles in some states, but not others.

Whether a vehicle is operable may also decide the outcome of a case. As a general rule, when a vehicle is incapable of operation, it is held not to be a vehicle for purposes of the DUI statute. A conviction was reversed where it was undisputed that the car in which the defendant was sitting was inoperable due to mechanical problems. Though an easy out, a vehicle’s inoperability is not always a guarantee. In one case a conviction was upheld even though the vehicle was out of gas but near a gas station. The court held that the situation made it "reasonably capable of operation."