Of course in most cities the law assumes that dogs are not well-trained (and that is unfortunately true of many), and so we all have to walk our dogs on a lead. But the real issue is not the leash: some dogs on a leash are more dangerous than a well-trained dog walking free. The key is control and proper training. The leash is one of the tools available to control a dog, like voice, electric collar, etc... the main problem is that many owners have no idea how to control their dogs, with a leash or without.