Trump administration forcibly separating asylum-seekers from their children, ACLU claims

— -- In a break from previous administrations, Donald Trump's Department of Homeland Security is forcibly separating asylum-seekers from their children when they arrive in the U.S., according to the American Civil Liberties Union.

A mother and her 7-year-old daughter escaping persecution and "near certain death" by fleeing the Democratic Republic of Congo have been separated for nearly four months, according to a legal complaint filed today by the ACLU.

Referred to in the case as "Ms. L" and "S.S.," the mother and daughter arrived in San Ysidro, California, Nov. 1. They told border guards they were seeking asylum, according to the court documents. Ms. L passed what's called a "credible fear interview," where an officer determined she and S.S. had a "significant possibility of ultimately receiving asylum."

Like many asylum-seekers, the two were detained while their application was processed. Under longstanding policy, families typically are kept intact at detention centers or released with a court date.

But just four days after arriving in the U.S., Ms. L was sent to Otay Mesa Detention Center in San Diego County while S.S. was ripped away from her and flown to another center in Chicago, according to the filing. S.S. speaks Lingala, a few words of Spanish and no English.

Contacted by ABC News about the case, a Department of Homeland Security spokesperson said the department does not comment on pending litigation.

The complaint claims, "When the officers separated them, Ms. L. could hear her daughter in the next room frantically screaming that she wanted to remain with her mother.” Ms. L said that no one involved in the process explained that her daughter would be taken away, to where she would be taken or when they would next see each other.

The mother and daughter spoke on the phone about five days after being separated, but have been apart ever since.

“Seven-year-old S.S. sits all alone in a Chicago facility, frightened and traumatized, crying for her mother and not knowing when she will see her again,” according to the court papers, which also claim Ms. L and her daughter had their due-process rights violated by DHS and other federal agencies.

This lawsuit will be "a legal test case" in how the current administration handles situations involving parents and children seeking asylum, said Lee Gelernt, Ms. L's attorney and deputy director of the ACLU's National Immigrants' Rights Project.

The ACLU has learned of hundreds of similar cases and intends to "attack this practice more broadly in the near future," Gelernt told ABC News. "We hope the administration will reconsider this horrific practice, but unfortunately we are hearing it may actually expand and formalize the practice into national policy."

In nearly three decades of civil rights work, Gelernt said Ms. L's case is among the worst he's seen.

"Listening to this mother describe her child frantically screaming when they took her away," he added, "was gut-wrenching."