The Formality of Judgeship

Almost all legal systems that I can think of have had some formality in who can act as a judge. In China, there were so many certain officials could act as magistrates and judges. In the Islamic world as well, there were the Cardis and appointees for caliphs. But there it was more the people who had real religious authority were mostly those who had religious training. They were respected on religious grounds, not just on legal grounds.