The principle that anyone born on a country's soil automatically becomes a citizen. In the United States it is grounded in the 14th Amendment, which says all those "born or naturalised in the United States, and subject to the jurisdiction thereof, are citizens." The amendment was passed after the civil war, in part to overturn the notorious 1857 Dred Scott Supreme Court decision, which held that black people were not and could never be American citizens.
The "jurisdiction" language had long been understood to create carve-outs only for children of diplomats or Native Americans. Some conservative scholars now argue the words imply a requirement for parental "allegiance" to America.
Birthright citizenship is common across the Americas, where settler societies used it as "an engine of assimilation." European countries have restrictions on it. Donald Trump has claimed the United States is the only country with birthright citizenship, which is untrue.
Research suggests birthright citizenship increases assimilation. When Germany reformed its citizenship rules in 2000, making them closer to the American system, economists found that immigrant parents subsequently spent more time with native Germans, spoke more German and enrolled their children in early education at similar rates to non-immigrant families.
Unlike most other countries, America has no central birth registry. States, counties and municipalities issue birth certificates; there are 14,000 different kinds in circulation. Birth certificates alone have been enough to prove citizenship. Only half of Americans have passports.
In 1898 the Supreme Court confirmed in United States v Wong Kim Ark that a child of Chinese nationals born in San Francisco was an American citizen. Since that ruling, birthright citizenship has been understood as universal, with exceptions only for offspring of diplomats, invading soldiers and (until 1924) Native Americans.
On January 20th 2025 Trump signed an executive order directing that only children of citizens and permanent residents could be granted birthright citizenship, excluding undocumented immigrants and people temporarily working or studying in America. Federal courts in Maryland, Massachusetts and Washington quickly blocked the policy. The judge in Washington, an appointee of Ronald Reagan, called it "blatantly unconstitutional." According to data from the Urban Institute, there are over a million American children under three with only non-citizen parents. The Niskanen Centre, a think-tank, estimates only a few thousand births a year result from "birth tourism."
After striking out in three appellate courts, the Trump administration asked the Supreme Court to weigh in on March 13th 2025. The case, Trump v CASA, was the administration's attempt to challenge universal injunctions blocking its birthright-citizenship order. The solicitor-general did not ask the justices to reverse the lower courts' rulings outright; instead, he asked them to narrow the injunctions to cover only the litigants in the cases, rather than the "hundreds of thousands" of people who may be affected. The court set oral arguments for May 15th 2025—an unusual step for its emergency docket.
The case is one of 13 emergency appeals from the Trump administration to reach the court in his second term, compared with a total of eight emergency pleas from the George W. Bush and Barack Obama administrations over 16 years combined.
On September 26th 2025 Trump asked the Supreme Court to let him deny birthright citizenship to babies born to non-citizens. The court is expected to take up Trump v Washington and rebuff his reading of the 14th Amendment.
After the Supreme Court sided with the administration on universal injunctions in Trump v CASA (June 2025), a court in New Hampshire blocked the order via a class-action suit. In December 2025 the Supreme Court agreed to hear the case. Oral arguments were held on April 1st 2026.
The administration argues that the 14th Amendment "was adopted to confer citizenship on the newly freed slaves and their children" and that the words "subject to the jurisdiction thereof" imply a requirement of parental "allegiance" based on domicile. Temporary visa holders are "domiciled elsewhere" and undocumented immigrants "lack the legal capacity to form a domicile", therefore neither's offspring qualify.
The challengers—and most legal scholars—point to Wong Kim Ark, in which Justice Horace Gray grounded citizenship in birth on American soil, not in the immigration status or legal domicile of the parents. The administration claims the ruling says nothing about the offspring of undocumented people, but the majority opinion swept broadly. Anthony Michael Kreis, a law professor at Georgia State University, says the administration's argument focuses on the status of the parents while the 14th Amendment is about the child. SCOTUSbot, The Economist's forecasting model, predicts the administration will lose by a vote of 5-4 or 6-3. Anna Law, a legal historian at Brooklyn College, notes the case arrives at a moment when the court has shown willingness to overturn long-settled precedents.
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