Justices Dubious of ‘Obscure’ Sources in Trump Birthright Case

US Supreme Court justices on both sides of the ideological divide sharply questioned the historical scholarship the Trump administration relied on to support its bid to overturn the constitutional guarantee of birthright citizenship.

Out of necessity, Solicitor General John Sauer at Wednesday arguments looked to sources outside the longstanding consensus on the 14th Amendment, which has treated birthright citizenship as settled law for more than a century. Sauer argued the amendment’s framers intended the provision to apply only to children of legal immigrants domiciled in the US.

Because the amendment’s text doesn’t support that interpretation, Justice Elena Kagan said Sauer appeared to search for “some more technical, esoteric meaning” in historical materials, noting the government’s brief at one point cited remarks made during President Abraham Lincoln’s funeral.

“You’re using some pretty obscure sources to get to this concept,” Kagan said.

Sauer defended President Donald Trump’s executive order that would deny citizenship to children born in the US to parents who lack legal status or are in the country temporarily. He argued that established exceptions for the children of foreign diplomats and invading armies show the 14th Amendment was never intended as a universal grant of citizenship.

Chief Justice John Roberts questioned whether those exceptions could plausibly extend to the tens of millions of people the executive order could potentially affect.

“I’m not quite sure how you can get to that big group from such tiny and idiosyncratic examples,” Roberts said.

Justice Neil Gorsuch also challenged Sauer’s source material.

“I’m looking at 1868—you’re telling me is when I should look, in the test for domicile—and the stuff you have about ‘unlawfully present’ is like Roman law sources you’re going to,” Gorsuch said in an apparent reference to work by University of Minnesota law professor Ilan Wurman the government cited favorably roughly a half dozen times in its brief.

Some of the justices appeared at times to be unconvinced by the authorities Sauer cited, Columbia Law School professor Elora Mukherjee said.

“A telling moment was when Roberts spoke up and described Sauer’s argument as ‘quirky’ and raised real questions about what Sauer is doing when he’s citing these sources,” Mukherjee said.

Even Justice Samuel Alito, who appeared the most receptive to the government’s position, focused on offering his own reading of US v. Wong Kim Ark, the court’s landmark 1898 decision holding that a US-born child of Chinese parents was a citizen.

Alito questioned whether Justice Horace Gray, who authored the majority opinion, referenced domicile to distinguish Wong Kim Ark’s parents—who were lawfully present but barred from naturalization under laws restricting Chinese citizenship—from other Chinese nationals brought to the US temporarily to work in harsh conditions on the transcontinental railroad.

Cecillia Wang, the ACLU’s national legal director who argued in defense of birthright citizenship, said Wong Kim Ark referenced domicile only because it was a stipulated fact in the case—not part of the rule the court adopted. The decision, she said, has been correctly understood to affirm birthright citizenship.

If the justices rule against the administration, they have several paths. They could, as Justice Brett Kavanaugh suggested, adopt the ACLU’s reading of Wong Kim Ark and affirm lower court rulings blocking Trump’s order.

“That could be just a short opinion, right?” Kavanaugh said, drawing laughter from the courtroom.

The court could also find the order barred by statute, pointing to a pair of mid-20th century laws codifying the 14th Amendment’s citizenship clause. Or, it could address the constitutional question directly—an approach the ACLU and its allies have urged to reaffirm that birthright citizenship is settled law.

Trump, who attended part of the argument, made no direct public statement afterward. In a post on Truth Social, he wrote that the US was “STUPID” to allow birthright citizenship.

A ruling from the justices is expected by July.

The case is Trump v. Barbara, U.S., No. 25-365, argued on 4/1/26.