'Basic norm' (German: Grundnorm) is a concept in the Pure Theory of Law created by Hans Kelsen, a jurist and legal philosopher.
Merkl was developing a structural research approach for the understanding of law as a matter of the hierarchical relationship of norms, largely on the basis of their being either superior or inferior to each other.
This has led to the further division within this debate concerning the currency of the term Grundnorm as to whether it should be read, on the one hand, as part and parcel of Hans Vaihinger's "as-if" hypothetical construction.
This has led to criticism from noted authors such as H. L. A. Hart, who refers to the theory as a 'needless duplication' of the 'living reality' of the courts and officials actually identifying the law in accordance with the constitution's rules.
This theory has been severely criticised by theorists like Hart and Lord Lloyd, though others, such as followers of various schools of the future development of the United Nations, including Grenville Clark and Louis B. Sohn of Harvard, who have strongly endorsed it.