It's always interesting how different the things are. In Germany it's allowed to and not uncommon that police pulls you over without any suspicion. Usually they have a reason to (initiated by the question "do you know why we stopped you?") but that's not a requirement. And if they pull you over they will always ask you for the license and your registration certificate which you better own and carry with you. I got pulled over twice so far. In the first case I was speeding a little and they suspected me to be drunk (which I wasn't), the second time ... erm I managed to ignore their right of way. A clearly marked police car with high-visibility battenburg markings, but coming out of a road which just never comes a car from at 6am... I got a (deserved) bollocking and they followed me through half the city then, but nothing else, luckily.