The Trump administration has expanded an experimental program designed to expedite the processing and deportation of asylum-seekers from all over the world, implementing the new policy in the busiest sector of the U.S.-Mexico border.

The program, dubbed Prompt Asylum Claim Review, or PACR, expanded earlier in December to Texas' Rio Grande Valley, a highly transited and patrolled area along the southern border. Hundreds of asylum-seekers have been subject to the policy since it debuted as a pilot program in the El Paso sector in October.

A Customs and Border Protection (CBP) spokesman confirmed the expansion Tuesday, saying the policy is no longer in the pilot phase. The spokesman also confirmed that more than 1,000 migrants have been placed in the program so far. In late October, Deputy CBP Commissioner Robert Perez said "several dozens" of asylum-seekers had been subject to the policy, which he noted was "modestly getting out of the gate."

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The program, one of a series of restrictive policies the administration rolled out in 2019 to deter U.S.-bound migrants, has been shrouded in relative secrecy since it started. In October, the Department of Homeland Security said it was a "whole of government approach" to fast-track the processing of migrant men and families subject to a sweeping asylum restriction, while providing them access to "protections and due process."

But advocates and immigration lawyers have described a completely different policy, saying it denies asylum-seekers due process, restricts access to attorneys and effectively ensures their prompt deportation. Earlier this month, the American Civil Liberties Union (ACLU) and its branches in Texas and Washington, D.C., filed a lawsuit against the program.

In this Wednesday, November 6, 2019, photo, Border Patrol agents holds a group thought to have entered the country illegally, near McAllen, Texas, along the U.S.-Mexico border. Eric Gay / AP

According to the attorneys, migrants subject to the PACR policy are not placed in the Migrant Protection Protocols (MPP) program, which has required about 56,000 asylum-seekers to wait in northern Mexico for the duration of their U.S. immigration proceedings.

Instead, these asylum-seeking migrants are detained by CBP agents and quickly given "fear of persecution" screenings while in the agency's custody.

The policy is a significant change from previous procedures because asylum-seekers not returned to Mexico were typically detained by Border Patrol for a few days or weeks and then transferred to Immigration and Customs Enforcement (ICE) detention centers, where they would undergo what is called "credible fear" interviews overseen by asylum officers.

Lawyers have typically been granted access to clients in ICE facilities to offer them advice before the interviews, but under the PACR program, they are not allowed to see and speak to their clients, who are detained in CBP facilities.

Asylum-seekers encountered near the Rio Grande Valley are being detained in "soft-sided" facilities inside the port of entry connecting Donna, Texas, with Mexico.

Not only do migrants not have access to counsel during their fear of persecution interviews, but the screenings under the experimental initiative are also more difficult to pass, the attorneys said.

This is because most non-Mexican migrants encountered by U.S. officials after July 16 are not eligible for asylum under a regulation allowed by the Supreme Court. The rule denies migrants access to the asylum system if they traveled through a third country to reach the U.S. and did not seek protection there.

The migrants subject to the PACR program can only seek lesser forms of relief known as withholding of removal and protection under the United Nations Convention Against Torture. Migrants seeking these protections — which do not offer a pathway to U.S. citizenship, unlike asylum — have a much higher bar to reach to demonstrate they would face persecution if returned to their home countries.

If they fail these more difficult interviews, which attorneys say most migrants will because of the short amount of time to prepare and the higher standard to pass them, migrants may request to have an immigration judge review the assessment.

Immigration judges stationed at the court at the Otero County Processing Center in New Mexico have been conducting reviews of credible and reasonable fear interviews of migrants detained in El Paso via telephone. A spokesperson for the immigration court system did not respond to questions about who is reviewing the results of fear of persecution interviews for migrants in the Rio Grande Valley.

Advocates have said some migrants subject to the policy were deported within two weeks of their apprehension — a departure from the typical months-long duration of an asylum case for those not placed in the program.

In addition to the third-country transit ban on asylum and the "Remain in Mexico" program, the Trump administration has taken other controversial measures this year to lower border apprehensions, which have dropped for six consecutive months since a 13-year monthly high in May.

The U.S. in 2019 secured agreements with Guatemala, El Salvador and Honduras to send asylum-seekers at the U.S.-Mexico border to those countries and have them seek protection there, despite rampant violence and widespread poverty. So far, only the accord with Guatemala has been implemented, with the U.S. rerouting some asylum-seekers from El Salvador and Honduras there in recent weeks.