The author analyses theoretical predecessors and the sources of the sociology of law in the works of Eugen Pusic. He considers Pusic to be the main theoretician of legal theory and of the sociology of law in Croatia. Further, he believes that there is certain logic of theoretical development, from the modern theory of organisation to sociology and sociology of law. The development of public administration and organisation studies towards the studies of society and legal theory is logical and it has happened elsewhere. The theory of organisation, which is ideologically and ethically less contaminated than the theories of the state, was a solid basis for analysing the phenomenon of the law. Organisation theory provides intellectual frameworks and practical recommendations to anyone dealing with legal issues, be they practical or theoretical. The problems can be understood within the theory-defined context without losing the connections with practitioners. The author underlines the influence of legal theoreticians and practitioners via the group 'Law and Society' as well as the interference of Luhmann's work with Pusic's opinions. Pusic's cooperation with Niklas Luhmann after 1976 was the turning point. Pusic acknowledged the importance of Luhmann's theory of complexity reduction that perfectly supplemented Pusic's interpretation of the law of requisite variety. The two scientists also share an inclination for creating complex and elaborated system theories in which legal norms are the pillars. Eugen Pusic's interest in the sociology of law was not accidental; it was a logical development and maturing of his theories. He claimed and accepted that the sociology of law is a domain of the new understanding of the law. It follows from his idea that values and legal norms reflect the unity of society and that the triad of objectives, interests, and values is a foundation for normative regulation, while normative regulation is the core of regulatory institutions. The consequences of the idea that there are different levels -- interactions, organisation (of institutions) and social systems -- lead to the issues of internal structure of the system, of the tasks of each of its elements, of the relationships that are developed, and of the methods used in the process. In modern societies, the systems of normative regulation are differentiated, while the main, legal system is in its internal rational operation free from the values and interests, but it is simultaneously surrounded by them, they are its environment, the social system. Both the systems of normative institutions and the systems of normative organisations tend to increase their diversity by differentiation. Occasional alterations in the manner of integration of those systems are achieved by respecting the principles of integrity, coherence, non-contradiction, and economy. From the contemporary aspect of this dynamics, one can easily recognise the notions of sovereignty, justice, legitimacy, choice, division of power, norms, ethics, and human rights. Adapted from source document.