A federal judge appointed by former President Joe Biden blocked the Trump administration on Friday from rapidly deporting migrants who previously had been paroled into the U.S. due to violence and oppression in their home countries.

U.S. District Judge Jia Cobb ruled that the Department of Homeland Security was trying to change the rules midgame for people who had been welcomed on a temporary basis.

"In a world of bad options, they played by the rules," Cobb wrote in her memorandum opinion. "Now, the Government has not only closed off those pathways for new arrivals but changed the game for parolees already here."

Cobb said the administration cannot dismiss migrants' pending proceedings in immigration court and immediately arrest them outside the courtroom with the intention of expedited removal.

"This case’s underlying question, then, asks whether parolees who escaped oppression will have the chance to plead their case within a system of rules," Cobb wrote. "Or, alternatively, will they be summarily removed from a country that — as they are swept up at checkpoints and outside courtrooms, often by plainclothes officers without explanation or charges, may look to them more and more like the countries from which they tried to escape?"

The judge estimated the number of migrants affected by her decision was "hundreds of thousands." However, GOP lawmakers and President Donald Trump's allies suggest the figure could be 1 million or more, Politico reported.

On Monday, three Democrat-appointed federal appeals court judges demanded an explanation as to whether the Trump administration has an official policy that requires the daily arrests of 3,000 migrants.

The 90-minute hearing, before a panel of the 9th U.S. Circuit Court of Appeals in San Francisco, California, concerned Justice Department attorneys' request that a stay be issued regarding a Los Angeles federal judge's earlier ruling that Immigration and Customs Enforcement activities were illegally conducted without reasonable suspicion.

Judge Ronald Gould, a Clinton appointee, ordered a DOJ attorney to determine the origin of the daily arrest figure and file the results with the court.

The Supreme Court in May let the Trump administration revoke the temporary legal status of hundreds of thousands of Venezuelan, Cuban, Haitian, and Nicaraguan migrants living in the U.S.

Reuters contributed to this story.

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