Hans Kelsen's Pure theory of law is actually a misnomer. It should read theory of pure law. By pure Kelsen meant that all elements impure to law had to be hived off to leave a remnant of material which is essentially legal. Accordingly all natural law, moral, religious, social, and other accretions that are not strictly law had to be eliminated. This type of positive law approach is therefore in the tradition of Austin.

At the same time, Kelsen believed that law was a human construct and a power system. His method exposed the logical structure of law and so enabled him to investigate where the authority or validity of law lay.

He found that the most concrete applications of legal rules (that is to say where legal rules apply to specific factual sitiations) derived their authority from less specific and therefore more general legal rules. This investigative process could theoretically be extended backwards until the most fundamental, general and authoritative legal rule or standard (or "norm" as he called rules) was reached. He believed that the logical structure of law could be likened to a pyramid with the most fundamental and authoritative norm (the "Grundnorm") at the top and the most particular norms (those which applied to particular concrete situations) at the base. The passage from general to particular is called "concretization". The Grundnorm is inherently stable but may change over time. There is a question over their status: do such things really exist at all or are they purely hypothetical?

Because a law is normative, it must be applied with causal rigidity. The system is one of power and this means that norms are imposed coercively. At its most concrete, norms are directions addressed to officials whereby they should enforce a norm using coercion upon transgressors. By the means of citizens following rules and officials punishing them where they fail to do so, citizens appropriate the various norms as standards of behaviour. The norms thereby acquire efficacy and are by and large observed.

It can be said that Kelsen's view is incomplete. While having logical coherence, causal efficacy and embodying a power structure, Kelsen's system has no regard for the actual social setting of the law. Nor does it explain how people come to feel obligated to obey legal rules. Nor are all laws of this coercive nature. For these criticisms it is necessary to look at the reaction to Kelsen expressed by H. L. A. Hart, the English jurist, in his book "The concept of Law".