A Review of the Types of Law and Its Role in Restricting Political Power in the view of Thomas Aquinas

St. Thomas Aquinas is one of the theologians who has made a major contribution to political system-making. The most important aspect of his efforts is the valuable observations left by him on legal issues. One of the most important of these issues is the "types of law and investigating ruler's jurisdiction”. Among the main questions arise are: that What is the nature of law? What are the types of law? What is the position of each law and what is its relations with other laws? Thomas Aquinas initially divides law into four types (eternal law, natural law, human law, and divine law) and investigates the relations of some of these laws with each other, the jurisdiction of human legislator in legislation and the effect of law on restricting the scope of political power. A close investigation of this subject according to Aquinas's political thought can lead to a more precise understanding of the political theology of medieval Christianity and the influence which such Muslim philosophers as Farabi and Avicenna had on Aquinas.