What Is Birthright Citizenship and How Does It Work?
Birthright citizenship grants nationality at birth based on where a person is born or who their parents are. Here is how jus soli and jus sanguinis work around the world, and why this centuries-old legal principle remains fiercely debated.
Two Paths to Citizenship at Birth
Every country must answer a fundamental question: who belongs? Most resolve it at the moment of birth through one of two ancient legal doctrines. Jus soli, Latin for "right of the soil," grants citizenship to anyone born on a country's territory. Jus sanguinis, "right of blood," ties citizenship to the nationality of one or both parents, regardless of where the child is born.
In practice, nearly every modern nation applies some blend of both principles. But the emphasis a country places on one over the other shapes immigration policy, national identity, and the lives of millions of people.
How Jus Soli Works
Under unconditional jus soli, a baby born on a country's soil is automatically a citizen—no application, no waiting period, no regard for the parents' immigration status. The United States and Canada are the most prominent examples. In the U.S., this right is anchored in the Fourteenth Amendment, ratified in 1868, which declares that "all persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States."
The amendment was adopted after the Civil War specifically to overturn the Supreme Court's infamous 1857 Dred Scott v. Sandford decision, which had denied citizenship to African Americans. Three decades later, the Court reinforced the principle in United States v. Wong Kim Ark (1898), ruling that a man born in San Francisco to Chinese immigrant parents was a U.S. citizen by birth.
Today, roughly 33 countries maintain unrestricted jus soli, according to the World Population Review. Nearly all are in the Americas—including Brazil, Mexico, Argentina, and most Caribbean nations. Scholars trace this pattern to colonial-era policies designed to attract settlers to the "New World."
How Jus Sanguinis Works
Most of Europe, Asia, and Africa rely primarily on jus sanguinis. Under this system, a child inherits citizenship from parents, even if born abroad. Germany, Italy, Japan, and South Korea all follow this model. A child born in Tokyo to two French citizens, for example, is French—not Japanese.
Some jus sanguinis countries add conditional jus soli elements. France grants citizenship to children born on French soil if they reside there for a set number of years. Germany, since a 2000 reform, grants citizenship to children born in Germany if at least one parent has legally resided in the country for eight years.
Where Countries Have Changed Course
Several nations have moved away from unrestricted jus soli in recent decades. The United Kingdom ended automatic birthright citizenship in 1983, requiring at least one parent to be a citizen or settled resident. Australia followed in 1986, India in 2004, and Ireland in 2005 after a referendum.
Perhaps the most dramatic case occurred in the Dominican Republic, which in 2013 retroactively stripped citizenship from people of Haitian descent, denationalizing roughly 200,000 individuals—a move that drew widespread international condemnation.
Why It Remains Contested
Supporters of jus soli argue it prevents the creation of permanent underclasses—people born and raised in a country who can never become full members of its society. The Fourteenth Amendment was written precisely to eliminate such a caste system.
Critics raise concerns about so-called "birth tourism," in which expectant parents travel to jus soli countries specifically so their children receive citizenship. They argue this exploits the system in ways its framers never intended.
The debate is not merely academic. In the United States, the question of whether the Fourteenth Amendment's Citizenship Clause can be narrowed by executive action is currently before the Supreme Court, making birthright citizenship one of the most consequential constitutional questions of the era.
The Bottom Line
Birthright citizenship is more than a legal technicality. Whether a nation follows jus soli, jus sanguinis, or a hybrid model reflects deep choices about belonging, national identity, and who gets to call a country home. As migration patterns shift and populations move, these centuries-old doctrines continue to shape the rights—and lives—of millions worldwide.
