ToplinePresident Donald Trump seemed to preemptively attack Supreme Court justices as “stupid” and “dumb”—ignoring a warning from Justice John Roberts about “dangerous” rhetoric—as they prepare to hear oral arguments Wednesday in a landmark case challenging Trump’s executive order limiting birthright citizenship.President Donald Trump speaks in the Oval Office at the White House on March 24 in Washington, DC. Getty ImagesKey FactsThe Supreme Court will hear oral arguments Wednesday in Trump v. Barbara, a case concerning the legality of Trump’s executive order saying babies born in the U.S. cannot be citizens if their parents aren’t U.S. citizens or permanent residents themselves.Trump claimed Monday morning the U.S. is “the only Country in the World that dignifies” the topic of birthright citizenship “with even discussion”—which is false—and expressed pessimism the Supreme Court would rule in his favor, after the court previously ruled against his signature tariff policy.Other countries are “laughing at how STUPID our U.S. Court System has become” while taking advantage of U.S. citizenship by birth, Trump claimed on Truth Social, adding, “Dumb Judges and Justices will not a great Country make!”The 14th Amendment grants citizenship to “all persons born or naturalized in the United States, and subject to the jurisdiction thereof,” which has long been interpreted as guaranteeing citizenship by birth in nearly all cases, except for children of foreign diplomats or enemy soldiers.The Trump administration has adopted a novel legal theory claiming children of undocumented immigrants or temporary U.S. residents are not “subject to the jurisdiction” of the U.S., with Trump’s executive order stating children born in the U.S. are not citizens unless at least one of their parents is a citizen or permanent resident at the time of their birth.Parents and children impacted by the decision, represented by the American Civil Liberties Union, have challenged the order in court, arguing it’s unlawful and the court should affirm the 14th Amendment guarantees citizenship to children even when their parents aren’t permanent residents or citizens.What To Watch ForThe court will hear oral arguments Wednesday in the birthright citizenship case and issue a ruling in the coming months, sometime before the court’s term ends in late June. Trump’s order limiting birthright citizenship is not in effect while the court is deliberating, meaning babies born in the U.S. to temporary or undocumented immigrants will still be granted citizenship at least until the court rules.Big Number255,000. That’s the approximate number of babies who would be affected by Trump’s executive order each year if it takes effect, according to the Migration Policy Institute and Penn State’s Population Research Institute. Surprising FactTrump’s order limiting birthright citizenship is part of the president’s broader crackdown on undocumented immigration. If it takes effect, the Migration Policy Institute projects the number of undocumented immigrants would significantly increase, however, estimating there would be an additional 2.7 million by 2045 and 5.4 million by 2075.Do Other Countries Have Birthright Citizenship?Yes. While Trump has claimed birthright citizenship is unique to the U.S., nearly 40 other countries have policies guaranteeing citizenship to people who are born there. Countries with birthright citizenship policies are largely concentrated in North, Central and South America and include Argentina, Brazil, Chile, Canada, Ecuador, Mexico, Pakistan and Venezuela, among others.Is “birth Tourism” An Issue?Trump has repeatedly railed against birthright citizenship by claiming people take advantage of it through “birth tourism,” meaning they travel to the U.S. specifically to give birth so that their children will have citizenship. “The World is getting rich selling citizenships to our Country,” Trump wrote Monday, referring to companies that charge foreign nationals thousands of dollars to help facilitate “birth tourism.” It’s widely disputed how many births each year are attributable to “birth tourism”: Republican lawmakers cited figures in a court brief claiming there have been up to 1.5 million Chinese nationals alone who have given birth in the U.S. over the past 15 years, while the Center for Immigration Studies has estimated there are a much lower 20,000 to 26,000 births attributable to “birth tourism” each year. The Niskanen Center, a nonpartisan think tank, has taken issue with the Center for Immigration Studies’ figures, which analyzed government figures on foreign-born mothers, and instead estimates there are actually less than 2,000 babies born out of “birth tourism” each year. While Trump and other Republicans have argued for restrictions to birthright citizenship in order to curb “birth tourism,” challengers in the birthright citizenship case have argued it has only a “marginal” impact in practice, and the government can impose other ways of restricting it—as it already does by refusing tourist visas to people who may be traveling to the U.S. to give birth. A coalition of 140 social sciences professors similarly argued in a brief to the court the practice “accounts for an infinitesimal proportion of the children who receive birthright citizenship each year.”Key BackgroundTrump issued his birthright citizenship order on his first day in office in January 2025, but it has never taken effect, as numerous courts immediately struck it down as unlawful. The Supreme Court considered a different case on the birthright citizenship order last term, ruling lower court judges representing a single state or region could not issue rulings that unilaterally block policies nationwide, but that case did not consider whether Trump’s executive order was lawful. Trump’s post Monday comes after the president has repeatedly attacked the Supreme Court in the wake of its 6-3 ruling striking down his tariffs as unlawful, with the president calling the high court “little more than a weaponized and unjust Political Organization.” He has also suggested he doesn’t trust the Supreme Court to rule in his favor on birthright citizenship—even as the court has ruled in his favor in his second term more often than not—saying after the tariff ruling he believes the court “will find a way to come to the wrong conclusion” on birthright citizenship. Roberts criticized the attacks on the court at an event in Houston on March 17, saying “personally directed hostility” against justices “is dangerous and has got to stop.”Further ReadingForbesJustice Warns Against ‘Dangerous’ Attacks On Supreme Court—After Trump Slammed JusticesBy Alison DurkeeForbesTrump Complains He’ll Lose Birthright Citizenship Case—Continuing Rant Against Supreme Court Tariff RulingBy Sara DornForbesSupreme Court Will Rule On Trump’s Challenge To Birthright CitizenshipBy Antonio Pequeño IVForbesSupreme Court Limits Judges From Blocking Some Trump Policies—But Punts On Birthright Citizenship RuleBy Alison Durkee