Why are German Shepherds police dogs?
I think many police departments now favor the The story seems to be that German Shepherds have gradually departed from the original selection criteria that made them good work dogs, intelligent, rather stand-offish, capable of aggression but trainable so that their aggressive tendencies are only released on command. The German Shepherds of a century ago were smaller dogs, and probably didn’t have the tendency toward hip dysplasia that causes trouble for some individuals. Current German Shepherds are probably more friendly in general disposition, but that's just my guess/
One of the good things about German Shepherds, in my opinion, is that they rarely turn fear into aggression. I had a rescue dog of indeterminate genetic heritage, a female, that had been brutalized by some guys and then dumped on the street. From that time she hated men. The day the rescue service brought her to me she walked right up to my horse and touched noses with her, but it took her much longer to get comfortable to me. Women visitors could walk right up to her, but not men. When she fought another dog her fury was unstoppable. If she had gone off on a human like that, probably only severe damage would have stopped her. That is what fear does to dogs.
My German Shepherd was looking worryingly aggressive at 8 months old. Finally I realized that he only started angrily barking when some stranger happened to become directly toward us (in the parking lot, for instance). Once I had taught him to see those individuals as not coming to us but to the car next to us (or whatever their real destination was) his aggressiveness dropped off considerably. He is also capable of detecting humans with aggressive vibes from even very large men who like dogs, are not afraid, and are not angry/aggressive toward me. These characteristics would probably make him a good police dog. His best weight is around 100 pounds, and he is plenty strong enough to pull me at the end of his leash (another subject of training that had to be accomplished for my own safety).