The princes and princesses ran around the entire country, earning support and followers so that they could use that power to earn more support from the government. It was a mechanism that allowed the government the highest authority during succession.
The Bill of Royal Axioms, a document that specified laws that not even the emperor could change, did not allow an emperor to appoint a successor. Instead, the right to appoint an emperor had implicitly fallen into the hands of the government. The ceremony to officiate the emperor was, by law, in control of the government. Thus the government was given the implicit power to decide the emperor.
'That's another reason why the princes and princesses are racing to appeal to the government,' Rui mused. 'This was probably done on purpose by the founding emperor, he probably foresaw the rise of powerful corporations and organizations of Martial Artists that could potentially take the succession into their own hands.'