Attorney General Jeff Sessions. (Mike Blake/Reuters)

The union for the nation’s immigration judges is fighting a government decision to strip a Philadelphia judge of his authority over 87 cases, arguing that the move sidelines judicial independence as President Trump seeks to ramp up deportations.

Immigration judges work under the Justice Department’s Executive Office for Immigration Review, though they have independent authority to determine whether the thousands of undocumented immigrants who come before them every year can remain in the United States through asylum or some other form of relief.

In a labor grievance filed this week, the National Association of Immigration Judges says the office undercut that authority when it removed Judge Steven A. Morley from overseeing juvenile cases that he had either continued or placed on temporary hold amid questions over whether federal prosecutors had adequately notified the subjects to appear in court.

The Justice Department said in a statement Thursday that “there is reason to believe” Morley violated federal law and department policy in those cases, but it did not offer any specifics. The statement said an investigation is ongoing.

Trump alarmed immigration judges in June by tweeting that anyone caught at the border, presumably including those seeking asylum, should be deported without a trial.

“When somebody comes in, we must immediately, with no Judges or Court Cases, bring them back from where they came,” the president wrote.

In its grievance, the judges’ union focused on a case involving Reynaldo Castro-Tum, a Guatemalan national who arrived in 2014 as a 17-year-old unaccompanied minor.

Castro-Tum’s current whereabouts are unknown, and he had not responded to recent court summonses. Morley temporarily closed his case in 2016, ordering the Justice Department to ensure that Castro-Tum was receiving the notices. He did the same with other similar cases.

Prosecutors appealed Morley’s decision, and the case eventually came to the attention of Attorney General Jeff Sessions, who chose to review it in January.

Sessions concluded that Morley was wrong to close Castro-Tum’s case and ordered it resolved within two weeks.

Amiena Khan, a New York-based immigration judge who is the union’s vice president, said the intervention further raised suspicions that the administration is looking to circumvent the judicial process and move to deport people faster amid a backlog of some 600,000 cases.

“This is another transparent way, surprisingly transparent in this instance, for the agency to come in and re-create the ideology of this whole process more towards a law enforcement ideology,” Khan said.

The system “is based on our ability to look at the facts and adjudicate the claim before us to our best ability and then render a decision,” Khan said. “Not being told by someone else how to rule.”

The union, which represents 350 judges, argues that Morely should get his caseload back. It is asking the Justice Department to assure all immigration judges that their independent authority won’t be undermined.

Immigrant advocates say the dispute highlights a fundamental flaw in immigration courts, where the judges work under the same department that is tasked with prosecuting cases. Several legal groups have renewed a push for federal legislation to overhaul the system so judges can operate more independently, either through a different branch of the Justice Department or as a separate tribunal court.

“We’re very concerned the immigration judges are simply being turned into law enforcement officers,” said Laura Lynch, senior policy counsel for the American Immigration Lawyers Association, which launched a national campaign this month to lobby members of Congress to support such legislation.