Believe it or not, there are many states where, even if your key is not in the ignition of your vehicle, you can be arrested and charged with DUI. Why? A certain aspect of the law known as "dominion and control." In many states, simple being in the car gives you dominion and control over the vehicle. The law essentially views it that if an officer finds you intoxicated in your car, he basically got there before you started to drive. In a way, it's accusing you of a crime before you commit a crime. This is a very shaky area of the law, but any criminal charge is serious and must be treated that way. So, yes, you could be sobering up in your car in some states, with absolutely no intention to drive, but if an officer discovers you sleeping it off, could arrest you and charge you with DUI. Remember, never operate a vehicle if you are under the influence of any substance.