On April 1, the United States Supreme Court heard oral arguments in Trump v. Barbara, a case that could fundamentally alter who qualifies as an American citizen. Trump attended the hearing in person — the first sitting president known to have done so — and watched as his Solicitor General faced a barrage of pointed questions from across the bench. The conservative-majority Supreme Court appeared broadly sceptical of the Trump administration’s position.AdvertisementBirthright citizenship, or jus soli (Latin for “right of soil”), is the principle that anyone born on a country’s territory automatically acquires citizenship at birth, regardless of their parents’ nationality or immigration status. The US is one of roughly 30 countries that offer automatic citizenship to nearly everyone born there.Also Read | For Indians, the American dream is getting more and more complexThis right flows from the Citizenship Clause of the Fourteenth Amendment, ratified in 1868 in the aftermath of the Civil War. The amendment was designed to reverse the Supreme Court’s infamous 1857 ruling in Dred Scott v. Sandford, which had held that Black people — enslaved or free — were not citizens of the US. The Fourteenth Amendment corrected this by declaring that “all persons born or naturalised in the United States, and subject to the jurisdiction thereof, are citizens of the United States.”The bone of contention has been the phrase “subject to the jurisdiction thereof”. The Supreme Court interpreted this language definitively in 1898 in United States v. Wong Kim Ark. Wong Kim Ark, a young man born in San Francisco to Chinese immigrant parents — who were, under existing US law, ineligible ever to become citizens themselves — was denied re-entry to the United States. By a vote of 6-2, the court rejected the government’s argument that he was not a US citizen, with Justice Horace Gray explaining that the Fourteenth Amendment “affirms the ancient and fundamental rule of citizenship by birth within the territory, in the allegiance and under the protection of the country, including all children here born of resident aliens.”AdvertisementOn his first day back in the White House on January 20, 2025, Trump signed an Executive Order which directed federal agencies to deny citizenship documents to children born in the United States if neither parent is a citizen or a lawful permanent resident. It targeted two categories of parents: Those present in the country illegally, and those present legally but only temporarily — on student, work, or tourist visas.The Trump administration argues that the words “subject to the jurisdiction thereof” were always understood to require more than mere physical presence — they require a parent who owes “direct and immediate allegiance” to the United States, which in practice means someone with permanent legal domicile here. Children of undocumented immigrants and temporary visa holders, the government argues, owe primary allegiance to their parents’ home countries and therefore fall outside the clause’s protection.The government’s counsel, Solicitor General D John Sauer, argued that the Fourteenth Amendment’s citizenship clause was enacted narrowly, to settle the citizenship of formerly enslaved people and their children, not to extend an unconditional guarantee to the children of all foreigners who happened to give birth on American soil. When Sauer pivoted to contemporary policy concerns — invoking birth tourism, the practice of travelling to the United States specifically to give birth — Roberts asked how widespread the phenomenon actually was. Sauer acknowledged that “no one knows for sure.” Roberts then observed that birth tourism was certainly not a problem when the Fourteenth Amendment was ratified in the 19th century, and that any modern policy concern could have “no impact on the legal analysis before us.” Sauer countered that the United States now exists in a “new world”. Roberts was unmoved. “It’s a new world. It’s the same Constitution,” he replied.Justice Neil Gorsuch found it “striking” how rarely the concept of domicile — the central pillar of Sauer’s argument — appeared in the congressional debates during the drafting and ratification of the Fourteenth Amendment. Justice Amy Coney Barrett (a Trump appointee) challenged Sauer on how his theory would apply to the children of newly freed slaves — the very people the amendment was written to protect — and told him his argument was “not textual.” Justice Brett Kavanaugh (another Trump appointee) pressed Sauer on why Congress had reenacted the identical “subject to the jurisdiction thereof” language in its 1940 and 1952 immigration statutes, knowing full well what the court had held in Wong Kim Ark, without attempting to narrow it. “One might have expected Congress to use a different phrase,” Kavanaugh said, “and yet Congress repeats that same language, knowing what the interpretation had been.”Cecillia Wang argued for the challengers that the Fourteenth Amendment established a “fixed, bright-line” rule with a closed set of exceptions that no executive order can expand. She pointed to what she called a “fatal concession” by the government: it was not asking the court to overrule Wong Kim Ark. The sweeping language of that decision, she argued, makes clear that the place of birth — not the parents’ immigration status — is what the Fourteenth Amendment asks about.Justice Sonia Sotomayor raised a concern that shadowed the entire proceeding: If the court accepted the government’s theory, what would stop a future president from applying it retroactively, stripping citizenship from people already born? Sauer insisted the administration sought only prospective application — but conspicuously declined to say his legal theory could not, in principle, apply retroactively.If the executive order took effect, according to a study by the Migration Policy Institute, more than 250,000 children born on American soil each year would lose citizenship. A ruling against Trump would mark the second defeat of his second-term agenda at the hands of the very court he shaped, following the earlier tariff ruling, and would deepen his administration’s already open hostility toward the judiciary. If the court rules in Trump’s favour, the consequences would extend well beyond immigration. Retroactive application — even if the current administration disavows it — could become a live legal question, placing the citizenship of millions of Americans born since 1868 in a cloud of uncertainty.you may likeThe case is also a litmus test for originalism — the judicial philosophy that interprets the Constitution through the lens of its original text, history and public meaning at the time of enactment. Originalism has been the dominant creed of the court’s conservative majority, but critics have long argued that it is applied selectively, serving as intellectual cover for politically convenient outcomes. The abortion ruling in Dobbs and the expansion of gun rights in Bruen both drew sharp accusations that the court’s originalist majority was cherry-picking history to reach conclusions it already wanted. Trump v. Barbara puts that charge to a direct test.A ruling is expected before the close of the court’s term in late June. After leaving the courtroom, Trump posted on Truth Social that the United States was “the only Country in the World STUPID enough to allow ‘Birthright’ Citizenship.” The court appears inclined to disagree.Pruthvirajsinh Zala is an advocate currently pursuing an LLM at the University of Cambridge