A person who believes they have had too much to drink to safely or legally drive may sit, lie, or fall asleep in their vehicle in a parking lot or parking space outside of a bar or restaurant, or may pull off the road and park to “sleep it off.” When the police observe a person occupying or sleeping in a parked car they may investigate if the car is illegally parked (on the side of the road or elsewhere) or for the stated purpose of checking on the well-being of the occupant of the vehicle.

After knocking on the window and attempting to wake the occupant of the vehicle the police will typically ask if the occupant was recently operating the vehicle and whether the occupant has had anything to drink. Based in part on the occupant’s answers to these questions the police may request the occupant submit to a breath or blood test, perform field sobriety tests, and may ultimately arrest the occupant for DUI/DWI.

Laws defining DUI/DWI criminal offenses vary from state to state and often include a person who is in physical control of a vehicle as being within the definition of operating a vehicle. Based on such a broad statutory definition of operating a vehicle—and depending on other factors such as (1) whether the occupant was in the driver’s seat of the vehicle or the back seat or passenger seat; (2) whether the vehicle’s engine was running; (3) whether the occupant was awake or asleep; and (4) whether the key, if any, was in the ignition—the police may arrest the occupant for DUI/DWI.

In Michigan, the laws regarding DUI/DWI (driving under the influence/driving while intoxicated) can apply to individuals who are in physical control of a vehicle, even if they are not actively driving. This means that a person who decides to 'sleep it off' in their car after drinking may still be at risk of a DUI/DWI arrest if they are deemed to be in control of the vehicle. Factors that law enforcement may consider include whether the individual is in the driver's seat, whether the vehicle's engine is running, the individual's location in the vehicle, and whether the keys are in the ignition. If the police find someone sleeping in a car, they may conduct a welfare check, and if there is suspicion of intoxication, they may ask questions, request a breath or blood test, or perform field sobriety tests. Depending on the responses and the evidence gathered, the individual could be arrested for DUI/DWI. It is important for individuals to understand that even with no intention to drive, being in a parked vehicle while intoxicated can lead to legal consequences under Michigan's DUI/DWI statutes.