This continent has three only three empires in the ruling position and as such their laws are different in some cases. The Fotia empire, home to Lucien Raizen and emperor Fei which Derik killed earlier has this strict policy that every mage or warrior must register and train through the Academy. With everyone registered, the empire can have a rough idea of how much military power a clan holds. Judging through Dean's memories he concluded that the Fotia empire simply had too many restrictions placed on their people and this was bound to backfire someday and that's why the coup happened.