A dog trained for protection is considered a “dangerous” dog in some jurisdictions & may need to be registered with the authorities. If you own a dog trained for this & command it to attack someone & the person gets hurt, it is likely you will be charged with a crime, unless you can prove you had no other choice or death and/or serious physical injury could result. You can rest assured that the bit person will sue you personally as well, which can cost you alot of money & effort. Unless you are in a profession or real situation that requires protecting your safety, for valid reasons, then I really don’t think you have any business training your dog for protection. Extensive knowledge is required to train for this properly & if done improperly, the consequences can be grave to humans & cruel to the dog. Dogs are naturally protective of their pack(family) & territory(home/yard) & most will step up to protect their owner in the right situation