Define the concept of Kelson's 'Pure Theory of Law' under Analytical School.

Hans Kelson is known for his 'Pure Theory of Law'. Kelson believed that the contemporary study and theories of law were impure as they were drew upon from various other fields like religion and morality to explain legal concepts. Kelson, like Austin was a positivist, in that he focused his attention on what the law was and divested moral, ideal or ethical elements from law. He discarded the, notion of justice as an essential element of law because many laws, though not just, may still continue as law. Kelson described law as a "normative science" as distinguished from natural sciences which are based on cause and effect, such as law of gravitation. The laws of natural science are capable of being accurately described, determined and discovered whereas the science of law is knowledge of what law ought to be. Kelson considered sanction as an essential element of law but he preferred to call it 'norm'. According to Kelson, 'law is a primary norm which stipulates sanction'. According to Kelson, 'norm (sanction) is rules forbidding or prescribing certain behaviour'. He saw legal order as the hierarchy of norms having sanction, and jurisprudence was the study of these norms which comprised legal order. Kelson distinguished moral norm with legal norm and said that though moral norms are 'ought prepositions, a violation of it does not have any penal fallout. The 'ought' in the legal norm refers to the sanction to be applied for violation of law. According to Kelson, legal-normative meaning is assigned to certain actions and not to others depending on whether that event is accorded any legal-normative by any other legal norm. This second norm gains its validity from some other norm that is placed above it. The successive authorizations come to an end at the highest possible norm which was termed by Kelson as 'Grundnorm'. Thus, Kelson's pure theory of law is based on pyramidical structure of hierarchy of norms which derive their validity from the basic norm. Grundnorm or basic norm determines the content and gives validity to other norms derived from it. In his view the basic norm is the result of social, economic, political and other conditions and it is supposed to be valid by itself.