What is the Grundnorm according to Kelsen's theory?

The Grundnorm, or basic norm, is a hypothetical norm that serves as the foundation of a legal system according to Hans Kelsen's theory of law. It is the ultimate source of validity for all other norms within a legal system, providing the basis for their legitimacy. The Grundnorm is not itself derived from any higher norm, but is instead posited as a necessary presupposition for the existence and functioning of a legal system. It is the starting point from which all other legal norms are derived through a hierarchical structure of norms.

The Basic Norm