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 Montana, the unauthorized use of a motor vehicle, often referred to as 'joyriding,' is a criminal offense. This crime is distinct from theft in that the prosecution does not need to prove an intent to permanently deprive the owner of the vehicle. Instead, it is sufficient to show that the individual used or operated the vehicle without the consent of the owner or a person authorized to give consent. Montana's laws regarding unauthorized use of a motor vehicle can be found in the Montana Code Annotated (MCA). Specifically, the offense is typically covered under Title 45 for crimes, and more detailed provisions may be outlined in the sections dealing with theft and related offenses. Penalties for unauthorized use can vary, but they generally include fines, potential jail time, and restitution to the owner for any damages incurred during the unauthorized use.