International Law Unequal Treaties in International Law
Elena Conde Pérez, Zhaklin Valerieva Yaneva
  • LAST REVIEWED: 12 April 2019
  • LAST MODIFIED: 25 March 2020
  • DOI: 10.1093/obo/9780199796953-0131


The “unequal treaties” (known also by the terms “unjust,” “coercive,” “predatory,” “enslaving,” “leonine”) refers fundamentally, but not exclusively, to a historical category of bilateral treaties concluded in the late 19th and early 20th century between European states, the United States of America (USA) or Latin American countries (states that fulfilled the standards of “civilization”), and Asian or African states (perceived as “uncivilized”). Therefore, most of these treaties were signed after military defeat or as a consequence of such a threat and often provoked dissatisfaction, as they were establishing a system of benefits for the “civilized” powers, while restricting the sovereignty of the “uncivilized” and subordinate states. Hence, the “uncivilized” was being put in an unequal position while negotiating, as the “civilized” imposed—because of its economic and military superiority—harsh restrictions and inequitable terms and extorted for special privileges through concession of territorial and sovereign rights, division of spheres of influence, opening of ports, enforcement of extraterritorial jurisdiction, acquisition of railways, mining, etc. That said, the first unequal treaty is the peace treaty between the Qing Empire (China) and the United Kingdom signed in 1842, known as the Treaty of Nanking. It was followed by similar agreements between the United States and Japan (Convention of Kanagawa, 1854), or between Korea and Japan (Treaty of Kanghwa/Ganghwa, 1876). After World War II, all states suffering from unequal treaties tried to revoke the established system but met with varying success. Nevertheless and despite being seen as a historical category, the idea of unequal treaties is believed to have its prolongation to the present. Thus, the idea that lies behind the concept of “unequal treaties” is often related to imbalance between the parties, whether formal or substantive; nonreciprocal rights; and obligations and/or a coercive form of conclusion regardless of it being a military, political, or economic form of coercion. Accordingly, a question arises as to whether any of these forms of inequality affects a treaty qualified as unequal: whether it is valid or null, whether there are grounds for its revision or amendment or causes to declare its termination or suspension. However, applying the current international law—both its conventional (Vienna Convention on the Law of Treaties) and customary sources—there are not enough foundations to affirm the existence of an autonomous category of “unequal treaties” and, above all, that they could possibly have some legal consequences.

General Overviews

Detailed doctrinal discussions on the history and development of the concept of “unequal treaties” can be found in Nozari 1971 and van Hulle 2016. Detter 1966 addresses the topic from a legal perspective in the context of the Sixth Committee discussions on the Soviet concept of “peaceful coexistence” and, as a conclusion, offers some solutions de lege ferenda. Caflisch 1992 also considers the problem of whether there is a rule providing nullity of the unequal treaties (general principles of law, customary law, or prohibition of coercion) or the possibility of their unilateral termination or amendment. Although these works refer to the legal dimensions, they do not terminate the discussions about the exact definition of aggression, use of force, coercion, and imposed treaties. Anyway, it is widely accepted that the majority of the “unequal treaties” provided clauses of extraterritoriality, most-favored nation, territorial cessions, and stationing of foreign military units among other restrictions. The inequality was evident in the nonreciprocal nature of the agreements as they conferred all rights to the great powers and imposed all duties on the less powerful countries. Craven 2005 searches for answers as to why the doctrine of “unequal treaties” is being denied a place in the modern international law, although that is not the author’s objective: “[its] resurrection . . . as a doctrinal category, nor [is it] to make any suggestions as to how the problem of inequality might be addressed” (p. 337) under the existing norms of the law of treaties. Aust 2005 briefly reviews some of the most cited works on the topic and concludes that, despite its legal irrelevance, the discussion on inequality is “useful since it helps to throw light on the treaty-making process” (p. 85). Markovic 1970 focuses on the discussions that took place during the Vienna Conference on the Law of Treaties and possible justifications to invalidate or terminate unequal treaties. Cassel 2012 represents a thorough historical approach to the unequal treaties concluded with Japan and China by foreign powers. The author centers his attention on the scope of the imposed extraterritoriality: concession of various rights and immunities to foreign citizens living and working in the Asian countries and the possibility, in case of a crime committed by the foreigners, that the court and the law by which the defendant is to be sued or prosecuted is the one of his own state/nationality. Jiangfeng 2016 makes a comprehensive overview of the category of unequal treaties and its implications for contemporary international law.

  • Aust, Anthony. “Unequal Treaties: A Response.” In Interrogating the Treaty: Essays in the Contemporary Law of Treaties. Edited by Matthew Craven and Malgosia Fitzmaurice, 81–85. Nijmegen, The Netherlands: Wolf Legal, 2005.

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    Aust states that “unequal treaties” refer mainly to 19th-century agreements and insists that the acceptance of the inequality as a ground for termination of a treaty would cause instability. He states that the cornerstone of international law is the legal equality among states even if they are unequal in political, military, or economic terms. He wonders if an exact criterion on inequality exists.

  • Caflisch, Lucius. “Unequal Treaties.” German Yearbook of International Law 35 (1992): 52–81.

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    While searching for a rule attaching legal effect to the “unequal treaties,” the author affirms that states are free to conclude and determine the agreement’s content. Caflisch reminds that there is no norm prescribing need of equal duties and that the inequality does not necessarily mean that a treaty is void or voidable (except in situations resulting from physical or military force).

  • Cassel, Pär Kristoffer. Grounds of Judgment: Extraterritoriality and Imperial Power in Nineteenth-Century China and Japan. New York: Oxford University Press, 2012.

    DOI: 10.1093/acprof:oso/9780199792054.001.0001Save Citation »Export Citation » Share Citation »

    The newly established legal order between the West and the Asian states in the 19th century was a result of international treaties, which differ significantly from those that introduced a colonial regime in other parts of the world. The main difference exists in the extraterritoriality: a characteristic that, although valid for all the treaties with Asian counties, had its differences across them.

  • Craven, Matthew. “What Happened to Unequal Treaties? The Continuities of Informal Empire.” Nordic Journal of International Law 74 (2005): 335–382.

    DOI: 10.1163/157181005774939896Save Citation »Export Citation » Share Citation »

    A historical perspective on the development of the idea of unequal treaties, analyzing in depth the elements of inequality, such as the status of the parties (revealing the problem of sovereignty), the context surrounding the conclusion of the agreements (connected to the problem of duress and revision), and the content and form of the treaties themselves (reflecting the problem of reciprocity).

  • Detter, Ingrid. “The Problem of Unequal Treaties.” International and Comparative Law Quarterly 15 (1966): 1069–1089.

    DOI: 10.1093/iclqaj/15.4.1069Save Citation »Export Citation » Share Citation »

    According to the author, legal equality means that states are equal before international law and share the same rights and obligations. Special attention is given to the validity of unequal treaties, as Detter argues that most of them are not to be null or void automatically, though such a possibility is recognized in extreme cases only. For coverage of the issue according to her later theory see International Law and the Independent State, 2nd ed. (Aldershot, UK, and Brookfield, VT: Gower, 1987).

  • Jiangfeng, Li. “Equal or Unequal: Seeking a New Paradigm for the Misused Theory of Unequal Treaties in Contemporary International Law.” Houston Journal of International Law 38.2 (Spring 2016): 465–498.

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    This contribution addresses the topic of unequal treaties in a very comprehensive perspective, trying to respond to main questions as, for example, what treaties are unequal, which of them could be invalidated under international law, and what are the main implications derived from this category in contemporary international law.

  • Markovic, Milan. “Les Traités Inégaux en Droit International.” Jugoslovenska Revija za Medunarodno Pravo 17 (1970): 264–283.

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    Revision of the category of “unequal treaties” at the Vienna Conference on the Law of Treaties (1968–1969) and the special committee on the principles of friendship and peaceful cooperation. Markovic analyzes doctrinal studies on unequal treaties from the perspective of their legitimacy and legality (pacta sunt servanda rule) to that of their possible revision and applicability of rebus sic stantibus and ius cogens as a way to terminate or invalidate them.

  • Nozari, Fariborz. “Unequal Treaties in International Law.” PhD diss., University of Stockholm, 1971.

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    In his PhD dissertation on unequal treaties, Nozari underlines some of their basic characteristics: (1) to be a result of (in)direct pressure, (2) applied by a powerful state, (3) in order to dictate the clauses of the treaty, (4) on a weaker contracting party. These features, in his opinion, are direct consequence of the existing inequality at the time of the creation of the treaty.

  • van Hulle, Inge. “Grotius, Informal Empire and the Conclusion of Unequal Treaties.” Grotiana: A Journal under the Auspices of the Foundation Grotiana 37.1 (2016): 43–60.

    DOI: 10.1163/18760759-03700003Save Citation »Export Citation » Share Citation »

    Historical survey of the category of unequal treaties. The author considers that their existence goes far back to the early modern age. This article goes into the early modern roots of unequal alliances and discusses how the Grotian analysis of unequal alliances influenced other authors of the classic law of nations.

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