In This Article Expand or collapse the "in this article" section Slavery

  • Introduction
  • General Overviews
  • Reference Works
  • The History of Slavery and the Slave Trade until the Early 20th Century
  • Slavery and the League of Nations
  • The Sociological Definitions of Slavery
  • “Contemporary,” “Modern,” or “Modern-Day” Slavery
  • Slavery in International Humanitarian Law
  • Proposal of a New Treaty
  • Enslavement in International Criminal Law
  • Slavery, Servitude, and Forced Labor
  • Slavery as a Form of Exploitation in the Definition of Human Trafficking
  • The Status of the Prohibition of Slavery Under International Law

International Law Slavery
Silvia Scarpa
  • LAST REVIEWED: 29 May 2014
  • LAST MODIFIED: 29 May 2014
  • DOI: 10.1093/obo/9780199796953-0097


Slavery had existed for thousands of years, when, finally, in the 18th century the abolitionist ideal gained momentum. Well before the affirmation of the international protection of human rights, a concept that emerged after the end of the Second World War, the fight against slavery and the slave trade propagated the idea of equal dignity and the intolerability of different statuses or treatments based on law or customs. However, the first international act adopted in this field, namely a Declaration adopted during the Congress of Vienna (1815), condemned only the slave trade. It is with the adoption of the Treaty of St-Germain-en-Laye (1919) that, for the first time, reference is made not only to the suppression of the slave trade, but also to slavery in all its forms. Subsequently, after the First World War, the League of Nations promoted the adoption of the 1926 Slavery Convention, a treaty that contains the first international definition of slavery and the slave trade. In 1956 the United Nations adopted a Supplementary Convention on the Abolition of Slavery, the Slave Trade and Institutions and Practices Similar to Slavery. Moreover, he prohibition of slavery is also included in many international human rights instruments. Finally, in the same way as the founding treaty of other international criminal tribunals, the Statute of the International Criminal Court includes enslavement among the acts constituting, under specific circumstances, a crime against humanity. Prohibitions of slavery and the slave trade in times of both peace and war are unanimously considered to be customary rules of international law, and they have attained the level of peremptory norms (jus cogens principles). Moreover, the International Court of Justice (ICJ) considers the prohibition of slavery as an obligation erga omnes. Despite all these achievements, the international law on slavery still faces many challenges, including those related to the interpretation of the definition of slavery included in the 1926 Slavery Convention; the blurred lines between slavery and other exploitative practices, including, servitude and forced labor, and activities as, for instance, trafficking in persons. In this respect, the reorientation of international attention toward contemporary, modern, or modern-day slavery has to a great extent avoided the issue of the definition of slavery today and has made an attempt aimed at dealing with relevant exploitative practices without carefully verifying whether such practices fit the 1926 definition of slavery. Finally, the international law on slavery confronts additional challenges, including the absence of strong monitoring bodies as well as internal inconsistencies and lax implementation of a system characterized by loopholes and lack of clarity.

General Overviews

General overviews on slavery in international law tend to take into consideration treaties adopted since the beginning of the 19th century and they all focus extensively on the 1926 Convention on Slavery and the 1956 Supplementary Convention on the Abolition of Slavery, the Slave Trade and Institutions and Practices Similar to Slavery (Gutteridge 1957, Quirk 2011, Allain 2012 and Saulle 1999). Moreover, Miers 2003 examine the legal abolition of slavery and places it in a historical context, providing a balanced analysis of the issue, covering almost two centuries. Decaux 2009 offers a concise but effective French introduction to the international law on slavery and other severe exploitative practices. Nanda and Bassiouni 1972 compares the international law system in place for the elimination of slavery and the slave trade and the one aimed at the white slave trade or traffic.

  • Allain, Jean. Slavery in International Law: Of Human Exploitation and Trafficking. Leiden, The Netherlands: Brill, 2012.

    DOI: 10.1163/9789004235731

    Examines slavery as well as practices considered as “lesser forms of exploitation.” Then categorizes all these practices as forms of human exploitation, which is the final purpose of human trafficking.

  • Decaux, Emmanuel. Les formes contemporaines de l’esclavage. Leiden, The Netherlands: Martinus Nijhoff, 2009.

    DOI: 10.1163/9789047441434

    Discusses the historical dimension of the abolition of slavery and the slave trade in international law and takes into consideration the definition of slavery, emphasizing the risk of dilution of such a concept, as opposed to the required need for a well-defined and strictly interpreted offense under penal law. It also considers the international instruments in place in combating the white slave traffic, trafficking in persons, and forced labor.

  • Gutteridge, Joyce A. C. “Supplementary Slavery Convention, 1956.” International and Comparative Law Quarterly 6.3 (1957): 449–471.

    DOI: 10.1093/iclqaj/6.3.449

    Considers the treaties against slavery and the slavery trade adopted before the Slavery Conventions. It also takes into consideration the drafting history of the 1956 Supplementary Convention and comments on the 1926 definition of slavery.

  • Miers, Suzanne. Slavery in the Twentieth Century: The Evolution of a Global Problem. Walnut Creek, CA: AltaMira, 2003.

    The most complete, detailed, and extensive account of the history of international relations and the developments of international law in the field of slavery and the slave trade, beginning with the rise of the antislavery movement in Great Britain in the 18th century and covering up to the end of the 20th century.

  • Nanda, Ved P., and M. Cherif Bassiouni. “Slavery and the Slave Trade: Steps towards Eradication.” Santa Clara Lawyer 12 (1972): 424–442.

    Analyzes the prohibition of slavery and the slave trade in international law starting from the Congress of Vienna (1815). Compares the system aimed at prohibiting slavery and the slave trade with the one dealing with the white slave trade or traffic and concludes that the latter was less effective because the basic values that permit that practice to be tolerated have never changed.

  • Quirk, Joel. The Anti-slavery Project: From the Slave Trade to Human Trafficking. Philadelphia: University of Pennsylvania Press, 2011.

    Takes into consideration the history of the antislavery movement, starting from legal abolition in the British Empire to the fight against contemporary exploitative practices, and focuses, in particular, on three of them, namely chattel slavery, debt bondage, and trafficking in persons. Makes reference to the slavery conventions and to the UN Trafficking Protocol.

  • Saulle, Maria Rita. “La Schiavitù.” In Dalla tutela giuridica all’esercizio dei diritti umani. Edited by Maria Rita Saulle, 15–26. Naples, Italy: Edizioni Scientifiche Italiane, 1999.

    Takes into consideration the treaties abolishing the slave trade and slavery adopted since the end of the 18th century, the 1926 and 1956 Slavery Conventions, and universal and regional human rights treaties. Considers the concept of forced labor to be incorporated into that of slavery. In Italian.

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