I've seen at least one very dominant police dog. I was at an IPO seminar and the dog was there in an attempt to correct it's "dirty biting". When the dog is called off the decoy, it would run back towards the handler, but then turn around for one more bite before finally obeying the command to return. It was a Romanian import GSD. When the dog was let out of the squad car, we were told not to look at it, or we might become a target.
Does law enforcement really need to buy such head strong-dogs for their departments? Sounds like a liability to me. Get a decent dog that obeys. Malinois love to obey, they do it much better than a GSD, who actually might think first.