Cops run through yards all the time and dogs do not just always attack them. People who advocate for Pitbulls here all the time say it is the owner and my dog will lick you to death. What kind of person keeps a dog of any breed who would attack another person or dog. If they do own a dog with that potential then they have to expect that no matter how well they secure that dog, if some situation where they do not have complete control of their dog can happen, it will to either the cops, other dogs or as is often the case invited guest.In either case not all dog breeds will attack in this situation. If your breed of dog requires this much supervision or is dangerous in certain situations then regardless of the triggers for that breed instinct this was inevitable. Better for the dog and the dog owner to have a rude awakening then as is often the case children who happen upon these inherently dangerous dogs. Ban the breed stop these deeds and end the debate over what is no more then a self fulfilling prophecy.