Natural law
Thomas Aquinas expounded the concept of Human Law, a distinct form of law alongside Natural Law and Eternal Law, in "Summa Theologica". Thomas asserted the primacy of natural law over man-made law, stating that where it "is at variance with natural law it will not be a law, but spoilt law" . The result of any such conflict is that the man-made law does "not oblige in the court of conscience" , since human law is a "determinatio" of divine or natural law, and a lower law cannot contradict a higher law. Natural law theorists and others have thusly challenged many man-made laws over the years, on the grounds that they conflict with what the challengers assert to be natural, or divine, laws.