Authorities representing the Trump administration have their work cut out for them as they try to convince the 9th U.S. Circuit Court of Appeals that the White House has the authority to end DACA.
The Deferred Action for Childhood Arrivals has protected roughly 700,000 people who were brought to the U.S. illegally as children or came with families that overstayed visas.
In January, a federal judge in San Francisco blocked the Trump administration's decision to end DACA. White House attorneys are now challenging that decision. They want the 9th Circuit to throw out that ruling.
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However, the 9th Circuit is widely considered the most liberal of the U.S. appeals courts, making a Trump administration win unlikely.
The 9th Circuit has ruled against Trump's travel bans and is also considering the president's executive order to cut off funding from so-called sanctuary cities that limit cooperation with federal immigration authorities. Trump has even said he has considered breaking up the court.
Legal experts believe the DACA decision appears likely to end up before the U.S. Supreme Court eventually.
The administration has been critical of the 9th Circuit and took the unusual step of trying to sidestep the appeals court and have the California DACA cases heard directly by the Supreme Court.
The high court in February declined to do so.
The appeals court began hearing arguments Tuesday afternoon.
DACA supporters staged a small rally at the Pasadena courthouse.
The Associated Press contributed to this report.