Pure Theory of Law is a book by jurist and legal theorist Hans Kelsen, first published in German in 1934 as Reine Rechtslehre, and in 1960 in a much revised and expanded edition. The latter was translated into English in 1967 as Pure Theory of Law. The title is the name of his general theory of law, Reine Rechtslehre. Kelsen began to formulate his theory as early as 1913, as a "pure" form of "legal science" devoid of any moral or political, or at a general level sociological considerations. Its main themes include the concept of "norms" as the fundamental building blocks of law and hierarchical relations of empowerment among them, including the idea of a "basic norm" providing an ultimate theoretical basis of empowerment; the ideas of "validity" and "efficacy" of norms; legal "normativity", complete separation from morality, and ideas relating to legal positivism and international law.The impact of the book has been enduring and widespread, and it is considered one of the seminal works of legal philosophy of the twentieth century. Source: Wikipedia (en)