Rule according to higher law
The idea of a law of ultimate justice over and above the momentary law of the state—a higher law—was first introduced into post-Roman Europe by the Catholic canon law jurists. "Higher law" can be interpreted in this context as the divine or natural law or basic legal values, established in the international law—the choice depending on the viewpoint; no matter the source, it is a law above the law. And it is in this capacity that it possesses the equal legal value for both the common and civil law jurisdictions, as opposed to natural law which is largely associated with common law. "To recognize the necessary connection between the rule of law as an ideal and well-constructed constitutional government does not and should not be taken to imply that all states can or should maintain the same constitutional structures in practice".
The rule according to higher law is a practical approach to the implementation of the higher law theory that creates a bridge of mutual understanding (with regard to universal legal values) between the English-language doctrine of the rule of law, traditional for the countries of common law, and the originally German doctrine of Rechtsstaat, translated into other languages of continental Europe as état de droit (French), estado de derecho (Spanish), stato di diritto (Italian), and Правовое государство (pravovoe gosudarstvo) (Russian). The latter doctrine is the product of continental European legal thought, which had adopted it from German legal philosophy. Its name can be translated into English as "state of law"—meaning the state in which the exercise of governmental power is kept in check by the higher law rather than by the changeable law established by this state.[citation needed] Amartya Sen mentioned that the legal theorists in ancient India used the classical Sanskrit term "nyāya" in the sense of not just a matter of judging institutions and rules, but of judging the societies themselves.
The Rechtsstaat doctrine (legal state, state of right, constitutional state, constitutional government) was first introduced by the German philosopher Immanuel Kant in his latest works completed after the U.S. and French constitutions had been adopted in the late 18th century. Kant's approach is based on the supremacy of country's written constitution created using principles of the Higher Law. This supremacy meant creating guarantees for the implementation of his central idea: a permanently peaceful life as a basic condition for the happiness and prosperity of the citizens. Kant was basing his doctrine exclusively on the idea of constitutionalism and constitutional government.