Elected Leaders: Just, and Ruling in the Fear of God

Regardless whether an elected leader is a person of faith, there is a universal principle rooted in the righteousness of God which mandates that those who rule over men be just, ruling in the fear of God. Why are some rulers and others ruled? Who or what decides who rules? What is to be the character of those who rule? And who ultimately is the Supreme Ruler and Judge of all the earth to whom all elected leaders are accountable and in whose place they rule?