Force and the Charter is a very complex problem. It imports not merely the place of force in the relations of States within the Charter of the United Nations, but also the residual rules of international law, which themselves are very much older-several centuries older at least-than the United Nations. These are the residual rules of international law, customary international law, as we call it, concerning the use of force, insofar as the Charter has not abrogated those rules.
"Force And The Charter In The Seventies,"
Syracuse Journal of International Law and Commerce:
1, Article 2.
Available at: http://surface.syr.edu/jilc/vol2/iss1/2