A US judge on Wednesday ruled against a programme offering deportation relief and work permits to immigrants brought to the country illegally as children, known as “Dreamers".
The ruling came despite an attempt by US President Joe Biden's administration to bolster the programme's standing with a new regulation.
The decision by US District Court Judge Andrew Hanen in Texas deals a new setback to the programme, called Deferred Action for Childhood Arrivals (Daca), and the 579,000 people enrolled in it and others who hoped to enrol in the future.
Mr Hanen, a Republican-appointed judge, found a regulation issued last year by Mr Biden's Democratic administration did not fix legal deficiencies that led him to find Daca unlawful in 2021.
He blocked new enrolments to the programme, which has been in place for more than a decade.
The ruling, which came in response to a lawsuit brought by Texas and other states, is expected to be appealed.
Thomas Saenz, president and general counsel of the Mexican American Legal Defensc and Educational Fund, which is representing Daca recipients in the lawsuit, said it would ultimately be up to higher courts, including the Supreme Court, to rule on the programme's legality and whether Texas proved it had been harmed by it.
The US Department of Homeland Security can continue to renew the status of those enrolled in the programme before Mr Hanen's 2021 ruling, Mr Saenz said.
Many Daca recipients speak English and have jobs, homes and families in the US.
Mr Hanen wrote that the order did not require US immigration authorities “to take any immigration, deportation, or criminal action against any Daca recipient, applicant or any other individual that would otherwise not be taken”.
The White House and the office of Texas Governor Greg Abbott did not immediately respond to a request for comment.
Mr Biden, who is seeking re-election in 2024, has made it a priority to defend the Daca programme, which was created in 2012 under former president Barack Obama when Mr Biden was vice president.
Texas and eight other states with Republican attorneys general said the programme breached federal regulatory law and saddled them with costs for education, health care and law enforcement.
In October 2022, the conservative-leaning 5th US Circuit Court of Appeals affirmed Mr Hanen's ruling against Daca, but sent the case back to him for reconsideration in light of Mr Biden's regulation formalising the programme.