A migration think tank estimates that nearly 300,000 undocumented people could face deportation, without seeing a judge, due to a new regulation that starts Tuesday.

But at least one immigrant rights group has already promised a lawsuit to stop expansion of fast-track removals.

To avoid a fast-track deportation process, an undocumented immigrant will have to prove they’ve been in the country for more than two years.  

“That is much more difficult to do, when you catch people on the street or in a factory raid,” said Muzaffar Chishti, director of the Migration Policy Institute’s office at New York University School of Law.

A lawsuit against expanding "expedited removals" could argue that there was no chance to give feedback, he said.

“I think it will also be challenged on the basis that due process does have a different meaning when people have established ties (to the United States),” Chishti said.

The American Civil Liberties Union has said that it will sue the government.