Rottweilers and Pit Bulls have long been bred and trained to attack each other and humans in the name of sport and 'protection'. The people who propogate this are the true crime. Could you adopt a Roddy that you didn't know was bred for violence? Of course. Should you be shot if this dog attacked someone, who was trespassing on your property? There aren't clear cut lines here except in cases of unprovoked attacks and owners who trained dogs to do just that.
Ever watch
Animal Precinct on Animal Planet? They found dead dogs in a car and yard that were mauled in dog fights. I didn't know those things still went on. It's just disgusting. I feel bad for both dogs-the ones who are trained to kill because of the life they were forced into and the dogs that are used as 'bait'.