It's the nature of the beast for adolescent dogs to challenge their owners. It is going to happen when the dog is between the ages of 1 and 2, usually. Some dogs never growl at their owners during this time, and challenge simply by disobedience, while others act out by growling at their owners or worse.
Training with consistency and with intelligence doesn't mean hanging the dog, nor shocking the dog. It doesn't mean you let the dog have his way, and tolerate his aggression toward his owner, either.
Good morning.
No one here is suggesting just up and hanging or shocking this dog! I wouldn't give any kind of advice on what is appropriate until I had seen both the dog and the handlers and can read something about them with my own eyes. It's somewhat irresponsible for any of us to describe corrective measures or any kind of dominance 'test' without knowing more about what they are all capable of.
I think it is important for these people to get in touch with a real dog trainer who is experienced with strong dogs, and take an obedience class at the very least. It'd be fun, and they'd end up with a better dog. To give advice on specific corrective measures that might be expected to work magic would distract from that need.
"It's the nature of the beast for adolescent dogs to challenge their owners"
This has not been my experience. The only one that has ever growled at me or been rebellious, was my Alpha dog.
I agree that it does not mean hanging the dog or using a shock collar. Those tools IMO do more harm than good. I have raised German Shepherds and the personality differences are like humans. Some take guidance well and once in a while you run into the Alpha male. You should always use the minimum of discipline, but you do need to be consistant in your demands. An Alpha personality dog will except nothing less.
If this family does not have the ability to get this dog under control, then finding him a home with the police where they have the experience to control that personality is far better than destroying him. He can be both a happy and useful part of our society.