The concept of 'grundnorm' as used in constitutional theory was developed by

Hans Kelsen, an Austrian jurist, developed the concept of the 'grundnorm' (basic norm) in his Pure Theory of Law. He argued that all legal norms derive their validity from a hierarchically superior norm, with the grundnorm being the ultimate source of validity for an entire legal system — essentially the constitution in modern states. John Locke theorised natural rights, Dicey propounded parliamentary sovereignty, and Montesquieu developed the separation of powers.