[“This takes away all hope”: Migrants in Mexico fear new rules on asylum.]

But immigration advocates and lawyers said these new measures have come at a high cost. They called the new tent courts secretive, assembly-line proceedings for lawful asylum seekers, and said the policy has subjected them to kidnapping, assault and extortion. Homeland security officials have denied the public and the news media access to the tent courts, but have allowed access to the courtrooms like the one in San Antonio where the judges hear the cases.

“The historic openness of immigration hearings has been a critical safeguard to prevent abuses,” said Lee Gelernt, a lawyer with the American Civil Liberties Union, which has fought many of the administration’s immigration policies in court. “The administration must ensure access to these hearings so that any illegality can be exposed, especially in the beginning, given the novelty of the new ‘Remain in Mexico’ process.”

Amnesty International plans to travel to South Texas next week to seek access to the tent courts, which are officially called “port courts” because they are built at ports of entry.

An official with the Department of Homeland Security, the agency that oversees Customs and Border Protection, said in a statement, citing “law enforcement priorities,” that while immigration court hearings were generally open to the public, “the nature of the temporary hearing facilities located on C.B.P. property makes these court operations unique from other immigration courts.”

On Thursday morning, several of those who appeared via teleconference at the Laredo tents were from Honduras, but others were from Cuba. They were part of the so-called Remain in Mexico program, under which those whose cases are in process are bused in from Mexico for their court hearings and then sent back across the border. Several of the migrants appearing on Thursday had first sought entry to the United States at an international bridge in Laredo on Aug. 14 or Aug. 15. Many were scheduled for further hearings on Nov. 7.

With the help of an interpreter, Judge Craig A. Harlow could see and hear the migrants over the video link, and the migrants appeared to hear him clearly and answered all of his questions. Few of them were represented by lawyers. Most sat alone or with their relatives at the table, telling the judge that they agreed to speak on their own behalf. Those who said they wanted to apply for asylum were allowed to do so by the judge, who instructed the officers in Laredo to supply the migrants with applications.

Lorena, the woman from Cuba, did have a lawyer, but her case was heard by the judge before her lawyer arrived in the courtroom in San Antonio. The judge gave her a new court date in November.