Birthright Citizenship

by

Iseult Honohan

• LAST REVIEWED: 15 March 2024
• LAST MODIFIED: 23 May 2024
• DOI: 10.1093/obo/9780199756223-0344

Introduction

Birthright citizenship refers to the legal status of citizenship when acquired through birth to a citizen parent (ius sanguinis) or birth in the territory of a state (ius soli). This is how most people acquire citizenship, often unconditionally and automatically at birth. A minority across the globe acquire citizenship through naturalization. Historically ius soli predominated from the Early Modern period, when those born in the sovereign’s territory automatically became their subjects. Ius sanguinis arose following the French Revolution, reflecting the free citizen father’s right to pass citizenship on to his child. Both forms spread globally through imitation and colonization. All states now award citizenship by birth; most have a combination of the two forms. But the strength of provisions varies. All states have substantial ius sanguinis provision; fewer have strong ius soli. In both, acquisition may depend on certain restrictive conditions related to parental birthplace or residence, marital status, gender, religion, ethnicity, or race. Until recently citizenship has been studied more by lawyers than political scientists, and birthright citizenship has received less attention than naturalization. Studies have tended to focus on the citizenship laws and policies of a limited number of states, mainly in the Global North. Only recently have studies covering a greater number and diversity of countries begun to emerge. Comparative scholars have sought to identify and explain different patterns of birthright citizenship provision related to the strength of ius soli and ius sanguinis. These have been interpreted variously as alternative models reflecting different national conceptions of citizenship, as determined by civil or common law traditions, or as dependent on histories of emigration, immigration, and colonization. Contemporary changes have been understood as a function of domestic electoral politics, developments in international law, norm diffusion among states, or a range of contingent contextual factors. Scholars dispute whether diversity of citizenship regimes has been succeeded by convergence. More complex typologies and indices, including birthright citizenship, have emerged, along with increasing availability of data on citizenship around the world. The justification of birthright citizenship has been much debated. Birthright citizenship has been seen as an appropriate way of allocating democratic membership, providing intergenerational continuity of citizenry, reducing the incidence of statelessness, and integrating immigrants. But ius sanguinis has often been criticized as exclusive and illiberal. It is debated whether ius soli is better justified, or if all forms of birthright citizenship should be seen as conveying arbitrary privilege and contributing to global inequality.

General Overviews

Most people acquire their citizenship on the basis of birth. Birthright citizenship comes in two distinct modes: birth to a citizen parent (ius sanguinis) or in the territory of a state (ius soli). In its classic form, birthright citizenship is automatic at birth. Spiro 2019 provides a good brief introduction to the historical evolution and present configuration of birthright citizenship. The articles in Shachar, et al. 2017 place it in the context of broader current research on citizenship. The two forms of birthright citizenship have sometimes been identified with contrasting ideal models of citizenship and national character: ius sanguinis as ethnic and ius soli as civic, classically articulated in Brubaker 2002 (cited under Origins and Evolution of Ius Soli and Ius Sanguinis Birthright Citizenship). This is now seen as too sharp a dichotomy and the contingent factors determining citizenship laws have been emphasized (Weil 2001). Rather than being mutually exclusive ways of allocating citizenship, ius sanguinis and ius soli now exist in different combinations in the laws of most states. Joppke 2010 identifies a degree of convergence in birthright provision; Weil 2001 emphasizes continuing diversity. Ius sanguinis is now the dominant form. It is provided in all states, though restrictions often apply for children born abroad to citizens. Ius soli is found in its classic, unconditional form principally in North America and South America. More conditional forms are found in other regions. Concise overviews of the global incidence of birthright provision are found in de Groot and Vonk 2018, Honohan and Rougier 2018, and (more briefly) Mignot 2019. Gender restrictions are still applied to ius sanguinis acquisition in a significant number of states, as documented in United Nations High Commissioner for Refugees 2023. While states are sovereign in setting their own citizenship laws, certain constraints that have developed in international law are outlined in de Groot and Vonk 2018 (see also Stratton 1992 [cited under Origins and Evolution of Ius Soli and Ius Sanguinis Birthright Citizenship]). The combination of the two forms of birthright citizenship gives rise to an increasing complexity of citizenship, and a discrepancy between the state’s citizenry and the population on its territory, as highlighted in Bauböck 2017. It also gives rise to dual citizenship. For discussion of this topic see the Oxford Bibliographies in Political Science article Dual Citizenship.

• Bauböck, Rainer. “Political Membership and Democratic Boundaries.” In The Oxford Handbook of Citizenship. Edited by Ayelet Shachar, Rainer Bauböck, Irene Bloemraad, and Maarten Vink, 60–82. Oxford: Oxford University Press, 2017.

  Addresses the question of defining the boundary of membership in democracies; identifies birthright provisions as one of the main elements of membership rules of modern states and outlines the way in which ius soli and ius sanguinis rules lead to a discrepancy between the membership and territory of states and make citizenship relations increasingly complex and transnational.

• de Groot, Gerard-René, and Olivier Vonk. “Acquisition of Nationality by Birth on a Particular Territory or Establishment of Parentage: Global Trends Regarding Ius Sanguinis and Ius Soli.” Netherlands International Law Review 65 (2018): 319–335.

  DOI: 10.1007/s40802-018-0118-5

  A clear, short, but comprehensive legal overview of contemporary global trends in provisions for both forms of birthright citizenship. Shows how these reflect both the autonomy of states in determining citizenship and the influence of international law. Also gives particular attention to ius soli provisions for otherwise stateless children, and for children following the recognition of paternity. A good introduction to the legal perspective.

• Honohan, Iseult, and Nathalie Rougier. “Global Birthright Citizenship Laws: How Inclusive?” Netherlands International Law Review 65 (2018): 337–357.

  DOI: 10.1007/s40802-018-0115-8

  A comparative survey of contemporary birthright provisions, based on the GLOBALCIT birthright database and indicators (see Data Sources and Indicators of Birthright Citizenship), distinguishing ius sanguinis provisions in the country and abroad, and ius soli provisions for first- and second-generation children of immigrants, for foundlings and for otherwise stateless children. The article identifies certain global patterns but finds no consistent pattern of inclusive ius soli provision in high immigration countries.

• Joppke, Christian. Citizenship and Immigration. Cambridge, UK: Polity Press, 2010.

  See especially chapter 1, “The Concept of Citizenship” (pp. 1–33), and chapter 2, “Status” (pp. 34–72). Discusses convergence in citizenship laws, especially in birthright provision. Outlines the changes in birthright citizenship provision, where ius soli has been made conditional in the United Kingdom, Australia, New Zealand, and Ireland, and moderate elements of ius soli introduced in Germany, Portugal, and Greece.

• Mignot, Jean-François. By Soil and Blood: Citizenship Laws in the World. La vie des idées, 2019.

  A highly accessible short introductory overview of global birthright citizenship provisions in 2019. Also published in French Par le sol et par le sang: Le droit de la nationalité dans le monde.

• Shachar, Ayelet, Rainer Bauböck, Irene Bloemraad, and Maarten Vink, eds. Oxford Handbook of Citizenship. Oxford: Oxford University Press, 2017.

  A major collection, with chapters by leading contributors in current scholarship from a range of disciplinary perspectives. This book provides a broader context for considering birthright citizenship, which is addressed more specifically in several chapters. For birthright, see especially chapters 4, 7, 9, 11, 12, 18, 21, 24, 25, and 34.

• Spiro, Peter J. Citizenship: What Everyone Needs to Know. Oxford: Oxford University Press, 2019.

  See especially chapter 1, “Citizenship through Birth” (pp. 21–60). A highly accessible introduction to the rationale and distribution of citizenship through birth in a question-and-answer format. Suitable for newcomers to the subject. Also includes a useful annotated bibliography covering citizenship more widely.

• United Nations High Commissioner for Refugees. UNHCR Background Note on Gender Equality, Nationality Laws and Statelessness. Geneva, Switzerland: United Nations High Commissioner for Refugees, 2023.

  A concise publication clearly outlining the restrictions on ius sanguinis transmission by women to their children found in global citizenship laws in 2023, with a focus on the implications for statelessness.

• Weil, Patrick. “Access to Citizenship: A Comparison of Twenty-Five Nationality Laws.” In Citizenship Today: Global Perspectives and Practices. Edited by Alexander Aleinikoff and Douglas Klusmeyer, 17–35. Washington, DC: Carnegie Endowment for International Peace, 2001.

  A short essay that expanded the scope of comparative research on citizenship laws, selecting twenty-five states globally and examining the role of historical legal traditions, the impact of emigration and immigration and the stability of borders in shaping citizenship regimes, and the balance of ius soli and ius sanguinis. Identifies continuing diversity rather than convergence between states in the years up to 2001.