Portugal Colonial - Supreme Court hearing landmark citizenship case -- with Trump in audience

The birthright case is a pillar in Trump's attempts to restrict immigration and his decision to attend oral arguments is unprecedented for a sitting president.

Trump signed an executive order on his return to the White House decreeing that children born to parents in the United States illegally or on temporary visas would not automatically become US citizens.

Lower courts blocked the move as unconstitutional, ruling that under the Citizenship Clause of the 14th Amendment nearly everyone born on US soil is an American citizen.

Solicitor General John Sauer, in his opening remarks to the court on Wednesday, said "unrestricted birthright citizenship contradicts the practice of the overwhelming majority of modern nations.

"It demeans the priceless and profound gift of American citizenship," Sauer said.

"It operates as a powerful pull factor for illegal immigration and rewards illegal aliens who not only violate the immigration laws but also jump in front of those who follow the rules."

Trump has spent the first year of his second term asserting extraordinary executive powers while attempting to sideline Congress and routinely pressuring the courts.

Just a week ago he attacked two of the Supreme Court justices whom he appointed during his first term because they voted against his tariff policies in another major case.

Trump has also called judges that did not side with him "rogue" and "criminal."

The birthright case tests who gets to be a citizen in a country built on immigration.

The 14th Amendment states that "All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States."

The Trump administration argues that the amendment, passed in the wake of the 1861-1865 Civil War, addresses the rights to citizenship of former slaves and not the children of undocumented migrants or temporary visitors.

- 'History and tradition' -

Trump's executive order is premised on the notion that anyone in the United States illegally, or on a visa, is not "subject to the jurisdiction" of the country and therefore excluded from automatic citizenship.

The Supreme Court rejected such a narrow definition in a landmark 1898 case involving a man who was born in San Francisco to parents who had come to the United States from China.

And Steven Schwinn, a law professor at the University of Illinois Chicago, said the court is likely to reject the challenge to birthright citizenship.

"This is a court that has looked to history and tradition as a significant guide in understanding the Constitution," Schwinn told AFP. "And it would be a little surprising if, after 150 years, we suddenly discovered we were applying the Citizenship Clause all wrong."

Conservatives have a 6-3 supermajority on the high court and three of the justices were appointed by Trump.

Sauer, in a brief with the court, said that in order to be eligible for citizenship "a person must be both born 'in the United States' and 'subject to the jurisdiction thereof.'"

"Children of temporarily present aliens or illegal aliens are not 'subject to' the United States' 'jurisdiction,'" Sauer said.

The American Civil Liberties Union, which is defending birthright citizenship before the court, said the Trump administration "is asking for nothing less than a remaking of our Nation's constitutional foundations."

If the Supreme Court does reject ending birthright citizenship, it would be the second major loss for Trump this term -- the justices struck down most of his global tariffs in February.

A decision in the case is expected by late June or early July.

F.Cardoso--PC