In the USA , I was in a class once, the instructor was a cop, so I asked him:
"if I was at a bar, and instead of driving home, I slept in my car, would I still get a DUI?"
His reply:
"If I can find your keys, then you are capable of operating the vehicle, and yes, you would get a DUI. But, if I cannot find your keys, then you are not physically capable of operating the vehicle. Tell you what, hide your keys in the wheel-well of your tire, no cop is ever going to look for them there, then just tell the cop you left your keys with the bartender."