In This Article Expand or collapse the "in this article" section Laws of War

  • Introduction
  • General Overviews
  • Collections, Commentaries, and Dictionaries
  • Data Sources
  • Textbooks
  • Bibliographies
  • Journals
  • Use of Force
  • Weapons
  • The Individual and the Laws of War
  • Crimes

International Relations Laws of War
Calin Trenkov-Wermuth
  • LAST REVIEWED: 02 March 2011
  • LAST MODIFIED: 02 March 2011
  • DOI: 10.1093/obo/9780199743292-0028


The laws of war are a set of rules that aim to regulate the acceptable reasons for going to war (jus ad bellum), the conduct of hostilities during a war (jus in bello), and the aftermath of a war and the transition from war to peace (jus post bellum). They are a part of public international law, and they derive from states’ desire to regulate the use of force, to prevent unnecessary suffering and destruction during a conflict, and to create a just and sustainable peace after a conflict. The laws that regulate the conduct of hostilities, also referred to as international humanitarian law, stem from two branches of law: the law of The Hague, which addresses the various types of weapons and their permissible uses, as well as the behavior of combatants during hostilities; and the law of Geneva, which deals with the humanitarian treatment of the victims of war, including the wounded, civilians, prisoners of war, and medical and religious personnel. Some of the underlying principles of the laws of war, also referred to as the laws of armed conflict in a broader sense, are that the wanton destruction of human life and property is prohibited, that protracted conflicts are not desirable, and that hostilities must swiftly come to an end once the political objectives that began a conflict are achieved. Combatants and civilians must be protected from unnecessary hardship or suffering, and if they fall into the hands of the enemy, key human rights provisions will apply to them. And the perpetrators of serious human rights violations must be held accountable. The laws of war are distinct from but may cover similar issue areas as a belligerent state’s national laws, which may also place legal limits on the potential justification for going to war or the conduct of that state during a war.

General Overviews

The laws of war can be a complex topic to study, especially for those without a legal background. A number of texts though provide a good introduction to this subject and manage to present it in an accessible way. They provide expert guidance through the legal jargon and key concepts and are useful for students of various fields, while maintaining their relevance for international lawyers and experts. The most important classic text on the laws of war is Grotius 2004, written by one of the founding fathers of international law. The three books contained in this seminal study have informed countless generations of scholars, lawyers, and military strategists and tacticians. Oppenheim 1952, edited by Hersch Lauterpacht, is as close as we can get to a modern-day classic of the 20th century. Howard, et al. 1994 provides a very useful general overview of the history and development of the laws of war over the centuries. Students and scholars should refer to Best 1996 for a more detailed and comprehensive analysis of the key developments since the end of World War II. Detter 2000 and Kennedy 2006 provide new and provocative interpretations of the uses and applicability of the laws of war. Kalshoven and Zegveld 2001 is a helpful introduction to humanitarian law for students and scholars, and Rogers 2004 should become a standard tool for all practitioners dealing with land warfare.

  • Best, Geoffrey. War and Law since 1945. Oxford: Clarendon, 1996.

    Authoritative treatise by an eminent thinker in the field. Surveys recent developments in international law as it relates to war, and explores various types of armed conflict since the World War II, offering a new perspective on ethics and the laws of war.

  • Detter, Ingrid. The Law of War. 2d ed. Cambridge, UK: Cambridge University Press, 2000.

    This well-structured and comprehensive account of the laws of war provides readers with a clear analysis of the key issues and challenges related to the application of such rules, and concludes that they are “binding” also outside treaties and on individuals, thus arguing for the subjectivity of individuals in international law.

  • Grotius, Hugo. On the Law of War and Peace. Whitefish, MT: Kessinger, 2004.

    Divided into three books, this true classic by a key luminary has shaped thinking on the laws of war since it was first published in 1625 and remains relevant and a must-read for any serious student of the laws of armed conflict.

  • Howard, Michael, George J. Andreopoulos, and Mark R. Shulman, eds. The Laws of War: Constraints on Warfare in the Western World. New Haven, CT: Yale University Press, 1994.

    An excellent history of the constraints on war, this edited volume expertly traces developments in the formal and informal regulation of violence from classical antiquity to the present, covering issues that range from weapons and combatants, to prisoners of war, war crimes, and civilians.

  • Kalshoven, Frits, and Liesbeth Zegveld. Constraints on the Waging of War: An Introduction to International Humanitarian Law. 3d ed. Geneva, Switzerland: International Committee of the Red Cross, 2001.

    Exposition of the main rules of humanitarian law, especially as related to weapons and international criminal law, this work is designed to be a useful tool for students and specialists alike.

  • Kennedy, David. Of War and Law. Princeton, NJ: Princeton University Press, 2006.

    Offers a provocative new perspective on the uses of the laws of war, arguing that law has become a tool of war itself, used to legitimize military action, and that it is no longer applied just for humanitarian ends.

  • Oppenheim, L. International Law: A Treatise. Vol. 2, Disputes, War and Neutrality. 7th ed. Edited by Hersch Lauterpacht. London: Longsmans, Green, 1952.

    Widely used and referenced by scholars and practitioners alike, this classic treatise by Oppenheim (the fifth edition edited by Hersch Lauterpacht, one of the most reputable scholars of his time) set the tone and industry standard for this subject for many decades.

  • Rogers, A. P. V. Law on the Battlefield. 2d ed. Huntington, NY: Juris, 2004.

    Well-written, logically constructed, and highly relevant book, which is the work of a former major general of the British Army. Examines key provisions of the laws of war as related to combat on land, tracing their origins and discussing contentious issues, and offering recommendations as to their practical application. This work will prove particularly useful to military planners and lawyers dealing with combat on land.

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