The Rule of Power - this is where it all started and would end at Adam's will.
Technically, The Rule of Power could be used by anyone against nobles, especially the higher nobles, because of their reputation's value and importance.
But... in practice, it wasn't that simple.
If the Twelve Branches families were to react to anyone who used The Rule of Power, then it would be an endless series of problems from hundreds or even thousands of people wanting to get even a tiny fraction of the wealth and power of the great families.
Therefore, to use The Rule of Power, one neededs a good and specific reason, clear motives, and a willingness to face the consequences.
For example: if two high nobles could not agree peacefully on some critical issue for their families, then, although very rarely, The Rule of Power was used.