The case centers on Trump’s order, signed after his return to the White House, which would deny automatic U.S. citizenship to children born on American soil to parents residing illegally or temporarily in the country.

Federal courts previously halted the measure, citing the Citizenship Clause of the 14th Amendment, which grants citizenship to nearly all individuals born in the United States.

The administration argues that the 14th Amendment, ratified after the Civil War, was intended to secure citizenship rights for formerly enslaved people and does not extend to children of undocumented migrants or temporary visa holders.

In filings, Solicitor General John Sauer contended that eligibility for citizenship requires both birth in the United States and being “subject to the jurisdiction thereof,” a phrase the administration interprets narrowly.

Lower courts rejected that interpretation, relying on longstanding precedent, including the 1898 Supreme Court ruling in United States v. Wong Kim Ark, which affirmed citizenship for a U.S.-born individual of foreign parents.Legal scholars cited in the proceedings said the court’s historical reliance on precedent may weigh against the administration’s position.

Steven Schwinn, a law professor at the University of Illinois Chicago, said the court has traditionally looked to historical practice in constitutional interpretation.Trump confirmed he would attend the hearing, marking a rare instance of a sitting president observing oral arguments in a case involving their own administration.

While presidents have historically maintained distance from court proceedings, Trump has previously attended judicial ceremonies, including the 2017 investiture of Justice Neil Gorsuch.

The Supreme Court currently has a 6–3 conservative majority, with three justices appointed by Trump during his first term.The administration has argued that automatic citizenship for children of undocumented migrants acts as an incentive for illegal immigration and so-called “birth tourism.”

Opponents, including the American Civil Liberties Union, said the policy would undermine constitutional protections and create uncertainty over the citizenship status of millions of Americans.

The case follows a separate setback for Trump in February, when the Supreme Court struck down much of his global tariff policy. Trump criticized that ruling and renewed his attack on judicial decisions ahead of the current hearing.

A decision on the birthright citizenship case is expected by late June or early July.

In a statement released late on Saturday, the ministry’s Hong Kong office said Commissioner Cui Jianchun met U.S. Consul General Julie Eadeh on March 27 and conveyed “strong dissatisfaction and firm opposition” to the alert, calling on the United States to stop intervening in Hong Kong matters “in any form.

”The dispute follows recent amendments to Hong Kong’s national security enforcement rules, which make it an offence in national security cases to refuse to provide passwords or other assistance to access electronic devices.

In response, the U.S. Consulate General in Hong Kong issued a public alert on March 26 advising U.S. citizens to contact the consulate if they are arrested or detained in connection with the updated rules.

The alert highlighted concerns over the expanded scope of enforcement powers under the revised framework.The U.S. Consulate General did not immediately respond to a request for comment outside business hours.

The exchange underscores ongoing tensions between Beijing and Washington over Hong Kong’s governance and legal environment, particularly since the introduction of national security measures that foreign governments have said could affect civil liberties and legal protections.

Chinese authorities have consistently defended the measures as necessary to safeguard stability and national sovereignty, rejecting external criticism as unwarranted interference.