I agree it's a shame to have dogs on leashes, but it's a law most place around where I live. My thought in your case was not to have him on the leash while walking, but only to have the leash handy, so that you could have attched it when you grabbed his collar, thereby having control without endangering your hands. Also, if there was a leash law, that would put the onus on the other person for injuries caused to you or your dog.