Why were we forced to remove tinted window film from our car windows by the police?

We stopped in a service area on the autobahn near Ulm last week. When we returned to our car after tea a police car was obstructing our exit. The policeman said the slight window tints on the front doors (installed by a previous owner) must be removed before we could proceed. My passenger and I are both in our late sixties. It was very difficult for us to remove the films just with our fingernails. It took nearly an hour and he watched as we struggled. It was humiliating and we were cold. We were also fined 120 Euros. He used no meter to measure the film. Just his own arbitrary decision. We had no idea we were breaking the law. Was his behaviour and on-the-spot fine correct please?

Asked on 7 December 2013 by RL, via email

Answered by Honest John
It happens in the UK too, and did on a recent traffic cops TV show. Ridiculous, because the tint only works one-way. It does not impede vision out of the car. But the cops like to be able to see and photograph the driver and front seat passenger. The UK has the greatest amount of camera surveillance in the world.
Similar questions
Can you tell me which is the best dash cam to fit on an Audi A1 Sportback rear privacy window? I have a Nextbase cam in the front window.
My son bought his first car, a Hyundai i10 Premium, on finance. The car came with black alloys and a carbon fibre black roof and tints in the back all done by the dealer. Now, a month after purchase when...
I am buying a new Ford Focus 1.0 litre hatchback and have been offered an "Appearance Pack" free of charge. This pack gives a slightly lower profile tyre but also tinted glass on the rear side windows...

Value my car