Reciprocity and the Law of War

70 Pages Posted: 7 May 2009 Last revised: 29 Apr 2015

See all articles by Sean Watts

Sean Watts

Creighton University School of Law

Date Written: October 21, 2008


This article examines how the principle of reciprocity operates within the international law of war. Tracing the historical development and application of the law, the Article demonstrates that the existing law of war derives from a set of rules that are highly contingent on reciprocity. Contrary to common understanding, reciprocity strongly influences states' interpretation and application of the law of war. The Article first identifies an obligational component of reciprocity that restricts operation of the law to contests between parties with parallel legal commitments. Second, the Article identifies an observational component of the principle that permits parties to suspend or terminate observance when confronted with breach. Although the principle of reciprocity was softened by late twentieth century legal instruments, it continues to form a critical component of the law of war and guides both pragmatic and theoretical discourse. Regardless of normative conclusions about reciprocity as a precondition to application of the law, the Article's reciprocity-cognizant framework for understanding the law of war provides a useful platform for reform efforts.

Keywords: Law of War, International Humanitarian Law, Law of Armed Conflict, Reciprocity

Suggested Citation

Watts, Sean, Reciprocity and the Law of War (October 21, 2008). Harvard International Law Journal, Vol. 50, No. 2, Summer 2009. Available at SSRN:

Sean Watts (Contact Author)

Creighton University School of Law ( email )

2500 California Plaza
Omaha, NE 68178
United States

Register to save articles to
your library


Paper statistics

Abstract Views
PlumX Metrics