The problem isn't just about drunk driving it's about being in charge of a vehicle when drunk. If you have the keys, then you have charge.
Originally Posted by Steve Smith
Martin's point about loose equipment was brought home to me many years ago whilst driving a company van through London in a somewhat lively fashion. An emergency stop caused equipment in the rear to try to leave the van via the front window. It was only the remains of the passenger seat that prevented it from doing so. Fortunately I was alone in the van otherwise I would have had a day or two in the coroners court to reflect on my poor driving. Since then I have always been very fussy about not having loose objects it the back of my car, I cannot claim that my driving has improved though.