That expedited removal process has for nearly three decades been used to quickly return migrants apprehended at the border. But in January, the administration expanded its scope to cover non-citizens apprehended anywhere in the United States who could not show they had been in the country for two years.

The policy mirrored one the Trump administration adopted in 2019 that Democratic President Joe Biden's administration later rescinded, and immigration authorities have made "aggressive" use of the new removal power in recent months, Cobb said.

But she said that unlike the population of migrants traditionally subject to expedited removal who were detained shortly after crossing the border, the group now being targeted had long since entered the country.

"That means that they have a weighty liberty interest in remaining here and therefore must be afforded due process under the Fifth Amendment," she said. "When it exponentially expanded the population subject to expedited removal, the Government did not, however, in any way adapt its procedures to this new group of people."