Citizenship has transformed from a narrow privilege held by a small class of free men in a single city to a concept so expansive that some scholars now discuss virtual citizenship for people whose nations may physically disappear beneath rising seas. Along the way, the rules about who counts as a citizen, what citizenship entitles a person to, and how it is acquired have been rewritten repeatedly, often in response to war, colonization, migration, and shifting ideas about human equality. The trajectory is not a neat line from exclusion to inclusion; gains in one era have been clawed back in another, and the meaning of the word itself has expanded far beyond what any ancient Athenian or Roman senator would recognize.
Citizenship in the Ancient World
The earliest Western model of citizenship emerged in the Greek city-states, where being a citizen of Athens or Sparta meant something intensely local. Citizenship was tied to participation in public life: voting, serving on juries, fighting in the military. It was also ruthlessly exclusive. Women, enslaved people, and foreign-born residents were shut out entirely, no matter how long they lived in the city or how much they contributed to its economy. The pool of citizens in classical Athens probably never exceeded a modest fraction of the total population.
Rome took a different approach. Roman citizenship started as a local status too, but the Republic and later the Empire discovered that extending citizenship could be a powerful tool for binding conquered peoples to the state. The most dramatic example came in 212 AD, when Emperor Caracalla issued the Constitutio Antoniniana, granting citizenship to virtually all free inhabitants of the empire. Scholars have long debated the motives. One analysis argues the edict was driven primarily by military needs: Caracalla wanted to widen the tax base to fund the army and solve recurring crises in recruiting Roman citizens for the legions by extending the pool of eligible soldiers across the entire empire.1Acta Classica Universitatis Scientiarum Debreceniensis. The reasons behind Constitutio Antoniniana and its effects on the Roman military Whatever the motivation, the result was a radical expansion: millions of people who had been subjects became citizens overnight. The parallel to later mass extensions of citizenship has not gone unnoticed. One legal comparison draws a direct line between Caracalla’s grant and the introduction of European Union citizenship in 1992, noting both as attempts to create a broad, “universal” citizenship across a sprawling political territory.2Maastricht Journal of European and Comparative Law. Second-Rate Citizens: Junian Latins and the Constitutio Antoniniana
Still, even Caracalla’s edict had limits. Certain categories of people, including the Junian Latins (freed slaves who held an inferior legal status), were likely excluded. The lesson from Rome is one that repeats throughout history: every expansion of citizenship has a boundary, and the people left outside that boundary often define the era as much as the people inside it.
The Nineteenth-Century Invention of Birthright Rules
If you grew up hearing that jus soli (citizenship by birth on a nation’s soil) and jus sanguinis (citizenship inherited from parents) are ancient legal traditions, the historical record tells a more surprising story. These two principles were not timeless categories inherited from Roman law. They were largely a nineteenth-century invention. Before the modern period, European empires assigned membership under various natural-law principles in which parentage and birthplace served mainly as evidence that a person belonged, not as competing legal doctrines.3Law and History Review. Inventing Birthright: The Nineteenth-Century Fabrication of jus soli and jus sanguinis
The shift happened as European states moved from natural-law thinking to positive law, where membership rules needed to be codified explicitly. Officials in multiple countries began prioritizing either birthplace or parentage as the basis for nationality, and by 1860 a French jurist named Charles Demolombe formally introduced the jus soli and jus sanguinis terminology into nationality law, framing them as competing, ancient traditions even though the binary was new.4Law and History Review. Inventing Birthright: The Nineteenth-Century Fabrication of jus soli and jus sanguinis That framing stuck, and today these remain the two main gateways to citizenship in the modern nation-state.5Regulation & Governance. Explaining the birthright citizenship lottery: Longitudinal and cross‐national evidence for key determinants
The practical difference between these two systems has had enormous consequences. Countries built on immigration, particularly in the Americas, tended to adopt jus soli rules because they needed to integrate newcomers quickly. Countries in Europe and East Asia leaned toward jus sanguinis, tying nationality to bloodlines and making it harder for immigrants’ children to become citizens automatically. Many modern states now use some combination of both, but the default rule still shapes who belongs and who doesn’t in deeply unequal ways depending on where a child happens to be born.
Who Was Excluded and How That Changed
For most of modern history, citizenship laws were explicitly built around exclusion by race, gender, and religion. The United States did not extend birthright citizenship to formerly enslaved people until the Fourteenth Amendment in 1868, and even afterward, naturalization was restricted to “white persons” and later “persons of African nativity or descent,” shutting out Asian immigrants for decades. The Chinese Exclusion Act of 1882 barred an entire nationality from naturalization. Similar racial criteria operated in other settler states: Australia’s “White Australia” policy, South Africa’s apartheid-era citizenship laws, and Canada’s restrictions on Indigenous and Asian communities all functioned to make citizenship a mechanism for racial hierarchy rather than equal membership.
Gender exclusions ran parallel. In many countries, a woman who married a foreign national automatically lost her own citizenship and took on her husband’s. The assumption was that a married woman’s political identity was subsumed by her husband’s. The United States did not fully guarantee independent citizenship for married women until the Cable Act of 1922, and even that law contained racial exceptions. Most European countries did not sever the link between marriage and women’s nationality until the mid-to-late twentieth century.
These exclusions were not merely historical curiosities. Research on contemporary naturalization in the United States finds that significant disparities persist. An analysis of naturalization adjudication data found that non-White and Hispanic applicants are less likely to be approved than non-Hispanic White applicants, that male applicants are less likely to be approved than female applicants, and that applicants from Muslim-majority countries are less likely to be approved than applicants from other countries, even after controlling for individual characteristics and variation between field offices.6PubMed Central. The importance of race, gender, and religion in naturalization adjudication in the United States Race, gender, and religion also interact to produce a hierarchy of outcomes, meaning the disadvantages compound for people who belong to multiple marginalized groups.7PubMed Central. The importance of race, gender, and religion in naturalization adjudication in the United States The formal legal barriers may have been removed, but the evidence suggests the process is not yet fully neutral.
Citizenship as More Than a Legal Status
Through most of the eighteenth and nineteenth centuries, citizenship meant primarily a bundle of civil and political rights: the right to own property, enter contracts, speak freely, and eventually vote. What it did not necessarily include was any guarantee of economic security or access to public services. You could be a full citizen and still starve.
The sociologist T.H. Marshall articulated the most influential framework for understanding how this changed. Writing in 1950, Marshall argued that citizenship evolved through three stages. First came civil rights in the eighteenth century: personal liberty, freedom of speech, the right to justice. Then came political rights in the nineteenth century: the right to vote and to participate in the exercise of political power. Finally, in the twentieth century, came social rights: the right to a minimum standard of economic welfare, education, and social security.8Journal of Humanities, Arts and Social Science. Evolution of Citizenship and the Construction of a Welfare State—The Connotation and Practical Significance of T.H. Marshall’s Citizenship Theory
Marshall’s framework helps explain why citizenship today feels so much thicker than it did two centuries ago. When modern democracies provide public education, healthcare, unemployment insurance, and pensions, they are enacting a version of social citizenship that earlier generations would not have associated with the concept at all. The welfare state, in this view, is not separate from citizenship; it is citizenship’s fullest expression. Of course, Marshall was describing the British experience, and the timeline does not map neatly onto every country. Many postcolonial states gained political independence in the mid-twentieth century and had to build civil, political, and social institutions nearly simultaneously, rather than in the tidy sequence Marshall described.
Decolonization and the Mass Creation of New Citizens
The collapse of European empires after World War II triggered one of the largest citizenship upheavals in history. Dozens of new nations came into existence across Africa, Asia, and the Caribbean between the late 1940s and the 1970s, and each had to define who belonged. The challenge was immense. Colonial borders had been drawn with little regard for ethnic, linguistic, or religious communities, so deciding who was a citizen of, say, newly independent Nigeria or Indonesia meant making choices that would entrench some groups and marginalize others.
In many cases, colonial subjects who had held no meaningful citizenship under empire were suddenly full citizens of a sovereign state. In other cases, people who had migrated under colonial labor schemes found themselves stranded without clear citizenship in either their country of origin or the new nation. The Indian partition of 1947, the expulsion of Asians from Uganda in 1972, and the ongoing statelessness of Rohingya people in Myanmar are all consequences of how decolonization drew citizenship lines.
The postcolonial period also created an enormous population of people with ambiguous nationality: born in one territory, ethnically linked to another, legally connected to a former colonial power. Britain, France, and the Netherlands all wrestled with how much citizenship access to grant to former colonial subjects, and the answers changed frequently. Britain’s immigration and nationality laws have been revised repeatedly since the 1948 British Nationality Act, each revision narrowing or reshaping who among the former empire’s subjects could claim British citizenship.
The Rise of Dual Citizenship
For most of the twentieth century, dual citizenship was treated as a problem to be prevented. The basic logic was that a citizen owed exclusive loyalty to one state, and holding two passports created conflicts of allegiance, especially during wartime. Many countries required immigrants to renounce their prior nationality upon naturalization, and some stripped citizenship from anyone who voluntarily acquired another.
That attitude has shifted dramatically. Research tracking global trends shows that dual citizenship has become increasingly accepted, with most of the change concentrated in the last two decades.9International Migration Review. “I Vow to Thee my Countries” – The Expansion of Dual Citizenship in the 21st Century A separate analysis using a dataset of expatriate dual citizenship policies worldwide since 1960 found that acceptance has grown from roughly one-third to about three-quarters of states globally over the past half century.10Migration Studies. The international diffusion of expatriate dual citizenship
Several forces drove the change. Sending countries realized that emigrants who kept their original citizenship maintained stronger economic ties, especially remittances. Receiving countries found that forcing renunciation discouraged immigrants from naturalizing at all, leaving large populations as permanent non-citizens. And in an era of cheap air travel and global communication, the old assumption that a person could live in only one national community at a time simply stopped matching reality. Today, millions of people hold two or even three passports and navigate multiple civic identities as a normal part of life.
Citizenship Revocation and the Return of Conditional Belonging
Even as dual citizenship expanded, a counter-trend emerged: the growing use of citizenship revocation as a security measure. After the September 11 attacks, and again during the rise of foreign fighters joining armed groups abroad in the 2010s, several Western democracies passed or expanded laws allowing the government to strip citizenship from individuals deemed a threat to national security. Britain, Canada, Australia, France, and others enacted or broadened denaturalization powers during this period.
An analysis of British case law on citizenship cancellation found that courts have tended to adopt a formal, legalistic approach, focusing on technicalities like whether the person holds another nationality rather than engaging deeply with questions about rights and belonging. The result, the analysis argues, is a minimal view of citizenship as a loyalty-for-protection bargain, reminiscent of the older concept of subjecthood from the era of empire rather than the rights-based citizenship that democratic states claim to uphold.11Law, Culture and the Humanities. Political Context and Meaning of British Citizenship: Cancellation as a National Security Measure
This is one of the more unsettling recent developments. The idea that citizenship is permanent and unconditional was central to post-World War II human rights thinking, partly in response to the Nazi practice of stripping citizenship from Jews and other persecuted groups before deporting them. Revocation powers reintroduce a tiered system in which naturalized citizens and dual nationals face a level of precariousness that citizens by birth in a single country do not.
Digital Residency and Citizenship Without Territory
Estonia launched its e-Residency program in 2014, and it remains the most prominent example of a state offering a form of membership entirely detached from physical presence. E-residents get a government-issued digital identity, the ability to start and run a business under Estonian jurisdiction, access to the country’s digital services, and a connection to the EU single market. What they do not get is the right to live in Estonia, vote, or use it as a travel document.
An ethnographic study of Turkish e-residents found that the program produces transnational forms of identity through digitalized business practices and platform-based interactions with the state, even though the participants never physically relocate. The researchers propose the concept of “digitalized migration,” in which individuals remain spatially immobile while integrating into another national context through digital infrastructure.12Global Networks. ‘There Is No Need to Come to the Country at All!’ Conceptualization of Digitalized Migration: An Ethnographic Research on Turkish e‐Residents
E-residency is not citizenship in any traditional sense. It does not grant political rights or guarantee physical entry. But it does something that would have been inconceivable even a generation ago: it unbundles some of the economic and administrative functions of citizenship from the physical territory of the state. Other countries are watching closely; several have launched or explored their own digital residency or digital nomad visa programs. The question these programs raise is whether citizenship can be meaningfully separated from place, and if so, what happens to the political and social dimensions that have always been part of the concept.
When the Territory Itself Disappears
Climate change is forcing a question that no legal framework was designed to answer: what happens to citizenship when a country’s territory is submerged? Several Pacific Island nations, including Tuvalu, Kiribati, and the Marshall Islands, face the prospect of becoming uninhabitable or losing their land entirely to rising sea levels within this century. Their populations are small, but the legal implications are vast. International law assumes that a state has a defined territory. If that territory ceases to exist, does the state cease to exist? And if the state ceases to exist, what becomes of its citizens?
Scholars have begun proposing creative solutions. One proposal envisions a hybrid, dual-citizenship model in which citizens of submerging nations would hold a jus sanguinis-based e-citizenship in their original state (which could persist as a legal entity even without land) alongside citizenship in whatever host state they relocate to. Another approach argues for virtual citizenship, a form of membership that persists despite non-residence.13SSRN. Climate Change and the Future of Citizenship. Three Essays Neither model has been tested in practice, but the fact that serious legal scholarship is building frameworks for stateless-by-climate populations shows how far the concept of citizenship has stretched from its origins.
Tuvalu has already taken a step in this direction. In 2023, it signed a treaty with Australia providing for a special visa category for Tuvaluan citizens, and its government has explored the idea of maintaining sovereignty in the digital realm even if physical territory becomes uninhabitable. These are not hypothetical scenarios anymore; they are policy discussions happening now, with real timelines attached. The Pacific Island cases push citizenship theory into genuinely new territory, where the assumed link between a people, a government, and a piece of land can no longer be taken for granted.