It is a criminal offense to use or operate a motor vehicle, boat, airplane, motorcycle, or other motor-propelled vehicle without the consent of the owner or other person authorized to give consent. This crime is generally known as (1) unauthorized use of a motor vehicle, (2) unauthorized use of a vehicle, or (3) joyriding.

The difference between this crime and the crime of theft is that the state does not have to prove a person charged with unauthorized use of a motor vehicle intended to keep the vehicle or permanently deprive the owner of the vehicle.

Laws regarding the unauthorized use of a motor vehicle vary from state to state and are generally found in a state’s statutes—often in the penal or criminal code or the vehicle code.

In California, the unauthorized use of a motor vehicle, commonly referred to as 'joyriding,' is addressed under California Vehicle Code 10851 VC. This statute makes it a criminal offense to drive or take a vehicle without the consent of the owner. The key distinction between joyriding and auto theft (covered by California Penal Code 487(d)(1)) is the intent behind the act. For a charge of joyriding, the prosecution does not need to prove that the individual intended to permanently deprive the owner of the vehicle, which is a requirement for a theft charge. Joyriding can be charged as a misdemeanor or a felony, depending on the circumstances of the case and the defendant's criminal history. Penalties for joyriding can include imprisonment, fines, and restitution to the vehicle's owner. It's important to note that this law applies not only to cars but also to other motor-propelled vehicles such as boats, airplanes, and motorcycles.