Cartel theory is usually understood as the doctrine of economic cartels. However, since the concept of 'cartel' does not have to be limited to the field of the economy, doctrines on non-economic cartels are conceivable in principle. Such exist already in the form of the state cartel theory and the cartel party theory. For the pre-modern cartels, which existed as rules for tournaments, duels and court games or in the form of inter-state fairness agreements,[1] there was no scientific theory. Such has developed since the 1880s for the scope of the economy, driven by the need to understand and classify the mass emergence of entrepreneurial cartels. Within the economic cartel theory, one can distinguish a classical and a modern phase. The break between the two was set through the enforcement of a general cartel ban after Second World War by the US government.[2]