A federal judge on Wednesday blocked Donald Trump?s attempt to restrict birthright citizenship in the United States in a blow to the president?s bid to end a right enshrined in the Constitution for more than a century.

The ruling indefinitely bans enforcement of one of Trump?s most controversial executive orders, which was due to come into effect nationwide on February 19.

?The denial of the precious right to citizenship will cause irreparable harm,? District Judge Deborah Boardman was reported as saying during the hearing at a Maryland court.

She noted that Supreme Court precedent protects birthright citizenship, adding that Trump?s order ?conflicts with the plain language of the 14th Amendment,? the Washington Post reported.

?No court in the country has ever endorsed the president?s interpretation,? she said.

?This court will not be the first.?

The injunction adds to a 14-day stay on enforcement of Trump?s executive order issued in January by a federal judge in Washington state.

There, US District Judge John Coughenour condemned the order as ?blatantly unconstitutional,? though Trump quickly told reporters he planned to appeal the ruling.

Birthright citizenship is enshrined in the US Constitution under the 14th Amendment which decrees that anyone born on US soil is a citizen.

Trump?s order was premised on the idea that anyone in the United States illegally, or on a visa, was not ?subject to the jurisdiction? of the country, and therefore excluded from this category.

His opponents have argued that the 14th Amendment, which was ratified in 1868 as the United States sought to recover from the Civil War, has been settled law for over a century.

They have cited an 1898 US Supreme Court ruling in the case of a Chinese-American man named Wong Kim Ark, who was denied reentry to the United States on the grounds that he was not a citizen.

The court affirmed that children born in the United States, including those born to immigrants, could not be denied citizenship. (AFP)

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