Preserving the Peace: The Continuing Ban on War between States

23 Pages Posted: 22 Jul 2008

Date Written: May 28, 2008


The history of international law is, in large part, about the development of restraints on states' right to resort to force in dealing with external conflicts. Today, states may use force only in self-defense to an armed attack or with Security Council authorization. Even in these cases, states may use force only as a last resort, and then only if doing so will not disproportionately harm civilians, their property, or the natural environment. These rules restricting force are found in treaties (especially the United Nations Charter), customary international law, and the general principles of international law. In other words, the three primary sources of international law yield important rules restricting the use of force. The rules on use of force, like all international law rules, are binding on states for the same reason the law of any jurisdiction binds - because it is accepted as law by the community.

The following remarks on the rules regulating the use of force are divided into three parts. Part I provides a brief history and overview of the current rules on the use of force. Part II applies these rules to assertions that the United States could lawfully attack Iran today. Part III then discusses why these rules are binding as law and answers arguments to the contrary. These remarks will, therefore, touch on the past, present, and future of the law on the use of force to preserve the peace between states.

Suggested Citation

O'Connell, Mary Ellen, Preserving the Peace: The Continuing Ban on War between States (May 28, 2008). California Western International Law Journal, Vol. 38, No. 1, 2008, Notre Dame Legal Studies Paper No. 08-23, Available at SSRN:

Mary Ellen O'Connell (Contact Author)

Notre Dame Law School ( email )

P.O. Box 780
Notre Dame, IN 46556-0780
United States
574-631-7953 (Phone)

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