In This Article Expand or collapse the "in this article" section Proportionality in International Law

  • Introduction
  • General Works
  • United Nations Human Rights Committee
  • International Criminal Law
  • Treaty Law

International Law Proportionality in International Law
Judith Gardam
  • LAST REVIEWED: 30 March 2017
  • LAST MODIFIED: 30 March 2017
  • DOI: 10.1093/obo/9780199796953-0147


In the most general terms proportionality requires a balance to be drawn between frequently conflicting values. Consequently, its application depends on a subjective value judgment and that very indeterminacy sometimes sits uneasily within law. Proportionality, nevertheless, is a pervasive and familiar concept within both the civil and criminal national legal systems of states. The norm first found expression in international law in the doctrine of the just war, the Christian version of which formed the basis of the secular just war writings of early commentators on the developing discipline of international law, such as Grotius and de Vattel. Nowadays the principle is reflected either explicitly or implicitly in several diverse areas of international law. It appears explicitly as either a treaty norm—as, for example, in the regulation of targeting decisions in International Humanitarian Law (IHL)—or as a customary norm in the case of self-defense and Countermeasures. In other situations, proportionality operates as a judicial mechanism of review implicit in the need to balance competing interests such as in European Union Law (EU Law), International Human Rights Law (IHRL), and the dispute settlement regime of the World Trade Organization (WTO). Proportionality is also a component of Maritime Law and Delimitation, the Law of Treaties, and International Criminal Law (ICL). The norm even has considerable support as constituting that elusive concept, a general principle of international law. The significance and scope of its role varies widely depending on the area of international law in question and determines to a considerable extent the amount of literature available on the topic. Despite its increasing importance in international law, exactly what proportionality requires of a particular decision maker in any given area of international law remains unsettled and is the subject of widespread judicial and scholarly debate. There is no one meaning of proportionality that is common in all contexts in which it operates or any consensus as to its application across the board. In order to provide some structure to the debate scholars have identified two major analytical approaches to the application of proportionality that they see reflected in state practice and jurisprudence: the so-called “quantitative” approach where the response is tailored or equivalent to the action against which it is to be measured, and the so called “qualitative” approach where other factors are to be taken into account. It is not suggested in the literature that all practice fits neatly into one or other category, but they are useful for the purposes of analysis and much of the material that follows incorporates these concepts.

General Works

Proportionality is an overarching principle of international law and not a discrete subject matter area. To date there is only one general work focusing on the topic by an acknowledged expert in the field: Cannizzaro 2000 (in Italian with a helpful but short English summary). An in-depth book review in English of Cannizzaro 2000, Mazzeschi 2002, provides a real sense of that work. Two excellent general coverages of the operation of proportionality in international law that very much reflect their authors’ common law and civil law backgrounds, respectively, are the article Franck 2008 and the book chapter Bardonnet 1994. Greig 1994, although not a general work as such, provides a lengthy and sophisticated analysis of the international legal system through the lens of reciprocity and proportionality in the law of treaties. Newton and May 2014 is a monograph that includes a chapter on the operation of proportionality in a number of contexts in international and domestic law and is interdisciplinary in nature. Finally, Higgins 1994, adopting the author’s preferred methodology of law as a process of decision making rather than a system of neutral rules, provides a concise overarching assessment of proportionality as part of the author’s General Course on International Law at The Hague Academy. All of these works take distinctive theoretical approaches to their topic and are useful to the reader who is searching for a sophisticated appreciation of the ways in which different scholars conceptualize the function of proportionality in international law. An introduction or overview to the topic can be found in Delbrück 1981–1991 that, although somewhat dated, is still informative, as well as in Crawford 2012. The majority of the general texts on international law contain brief references to proportionality, particularly when discussing the legal norms governing the Use of Force and IHRL. Any more detailed consideration of its application, however, is left to the growing but still relatively few specialist texts, monographs, and articles that consider the role of proportionality in their coverage of particular areas of international law and are detailed under the following headings: Countermeasures; European Union Law; International Criminal Law; International Human Rights Law; International Humanitarian Law; Maritime Law and Delimitation; Treaty Law; and the Use of Force.

  • Bardonnet, Daniel. “Quelques observations sur le principe de proportionnalité en droit internationale.” In Le droit internationale dans un monde en mutation: En Hommage au Professeur Eduardo Jiménez de Aréchaga. Vol. 2. Edited by Manual Rama-Montaldo, 995–1036. Montevideo, Uruguay: Fundación de Cultura Universitaria, 1994.

    Adopting the quantitative/qualitative dichotomy, the author provides an insightful assessment of the measurement of proportionality in various areas of international law.

  • Cannizzaro, Enzo. Il principio della proporzionalità nell’ordinamento internazionale. Milan, Italy: Giuffré, 2000.

    A thoughtful, in-depth study of the role that has been accorded to proportionality in international law generally by a prolific and distinguished writer on the topic.

  • Crawford, Emily. “Proportionality.” In The Max Planck Encyclopaedia of Public International Law. Edited by Rüdinger Wolfrum. Oxford: Oxford University Press, 2012.

    Brief but useful overview of the development of proportionality as a principle of international law from the time of Aristotle up to the era of the 1949 United Nations Charter.

  • Delbrück, Jost. “Proportionality.” In The Encyclopedia of Public International Law. Vol. 3. Edited by Rudolf Bernhardt, 1140–1144. New York: New Holland, 1981–1991.

    A succinct but informative overview that traces the historical origins and development of proportionality and its transition into domestic and international legal systems.

  • Franck, Thomas M. “On Proportionality of Countermeasures in International Law.” The American Journal of International Law 102.4 (2008): 715–767.

    DOI: 10.2307/20456680

    In a masterly, broad-ranging inquiry, Franck applies to proportionality his trademark methodology of the power of legitimacy in furthering compliance with legal norms.

  • Greig, D. W. “Reciprocity, Proportionality and the Law of Treaties.” Virginia Journal of International Law 34.2 (1994): 295–403.

    A lengthy and sophisticated assessment of the role of proportionality (and reciprocity) in remedial actions for treaty breaches, which provides the reader with a real sense of the function of proportionality in international law generally.

  • Higgins, Rosalyn. Problems and Process: International Law and How We Use It. Oxford: Oxford University Press, 1994.

    One chapter of this work applies the author’s hallmark methodology of treating international law as a decision-making process to demonstrate how proportionality (and equity) operate to “ease” the application of the norms of international law in “particular cases” (p. 219).

  • Mazzeschi, Ricardo Pissilo. “Review of ‘Il principio della proporzionalitá nell’ordinamento internazionale’.” European Journal of International Law 13.4 (2002): 1031–1036.

    DOI: 10.1093/ejil/13.4.1031

    A succinct but useful assessment of the contribution of the cited monograph by Cannizzarro to the literature.

  • Newton, Michael, and Larry May. Proportionality in International Law. New York: Oxford University Press, 2014.

    The primary focus of this work is proportionality in armed conflict and the discussion is explicitly “soldier-oriented” and matches theory against practice. It is a mix of philosophical, ethical, and legal concepts.

back to top

Users without a subscription are not able to see the full content on this page. Please subscribe or login.

How to Subscribe

Oxford Bibliographies Online is available by subscription and perpetual access to institutions. For more information or to contact an Oxford Sales Representative click here.