The international system with several influential states as global participants, as it existed prior to the US declaration of independence in 1779 until the beginning of the Cold War in 1945, is generally labelled multipolar. International law was during that period codified only to a low degree. Customary and treaty-based regulations concerning the use of force have formed with increasing clarity over the course of time.

The possibility of forming a balance of power in such a multipolar system, and the consequences of this for the actions of other states with regard to international law is considered to be a decisive factor in the development of international law during this period. However, with regard to the question of polarity of a system of states the respective geographic scope has always to be kept in mind.

The Monroe Doctrine

On 2 December 1823 the fifth President of the United States of America, James Monroe, in his annual address to Congress described principles of US foreign policy, which in the following period have been considered as points of reference for the long-term orientation of US foreign policy. The term ‘Monroe Doctrine’ to describe the principles laid down in this speech appeared in a debate in Congress in 1853. Different principles concerning the use of force and different claims of law with regard to the legality of the use of force have been put forward within the frame of the Monroe Doctrine.