The US Supreme Court on Tuesday rejected President Donald Trump’s bid to restrict birthright citizenship, ruling that children born in the United States to parents who are in the country illegally or on temporary visas remain entitled to automatic US citizenship.

In the closely watched decision delivered on the final day of the court’s term, the justices ruled 6-3 to preserve the constitutional right to citizenship for nearly everyone born on US soil.

Trump had signed an executive order on the first day of his second term directing that children born to parents living illegally in the United States or holding temporary visas would no longer automatically qualify for US citizenship.

Lower courts blocked the order, holding that the Citizenship Clause of the 14th Amendment guarantees citizenship to nearly everyone born within the United States.

The Supreme Court upheld that interpretation in a majority opinion written by Chief Justice John Roberts.

“Children born in the United States to parents unlawfully or temporarily present are ‘subject to the jurisdiction’ of the United States and are citizens at birth under the Fourteenth Amendment’s Citizenship Clause,” Roberts wrote.

In an unprecedented move for a sitting US president, Trump personally attended oral arguments before the Supreme Court in April.

He remained in court for submissions by Solicitor General John Sauer but left before arguments presented by Cecillia Wang of the American Civil Liberties Union, who defended birthright citizenship.

Trump’s attempt to end birthright citizenship formed part of his broader immigration agenda, which includes the deportation of millions of undocumented migrants.

During oral arguments, Sauer argued that unrestricted birthright citizenship encourages illegal immigration and so-called “birth tourism”, whereby foreign nationals travel to the United States primarily to give birth.

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 provision does not extend to those outside US jurisdiction, such as the children of foreign diplomats.

The Trump administration argued that the amendment, adopted after the 1861-1865 Civil War, was intended to secure citizenship rights for formerly enslaved people rather than the children of undocumented migrants or temporary visitors.

The administration further contended that individuals living in the United States illegally or on temporary visas are not “subject to the jurisdiction” of the country and should therefore be excluded from automatic citizenship.

The Supreme Court rejected that interpretation, citing its landmark 1898 ruling in the case of Wong Kim Ark.

Born in San Francisco in 1873 to Chinese parents, Wong Kim Ark was denied re-entry into the United States after travelling to China because of the Chinese Exclusion Acts.

The Supreme Court ultimately ruled that he was a US citizen by virtue of his birth on American soil.

The decision marks Trump’s third major legal defeat before the Supreme Court this term. The justices struck down most of his global tariff measures in February and, on Monday, blocked his attempt to remove Federal Reserve Governor Lisa Cook from office.