The night Gelernt told me her story, he was taking a break from writing a brief to be filed in two days, on March 9, amending her case into a nationwide class-action suit. “We just got a bunch of declarations in the last 15 minutes from people who work in detention centers down in Texas. They’re saying they’re seeing hundreds of cases.”

Ms. L. was paroled from detention the following week, a few days before the government’s response was due in her lawsuit. When I asked Gelernt why she had been released, he guessed it was an attempt to act as if her case had nothing to do with a policy of family separation. At the time, the government’s justification for separating Ms. L. and S. was that it needed to verify that Ms. L. was neither a child trafficker nor an abusive parent, though both of those things could have been ascertained quickly and without separating them.

A few days after she was released, Ms. L. traveled with an A.C.L.U. staff member from San Diego to Chicago. She was terrified to make the trip, certain that she would be arrested in the airport and sent back to Congo without ever seeing S. again. I met her briefly the next day, in a shelter on the outskirts of the city. Gelernt had gotten assurances from the government that Ms. L. and S. would be reunited, but he didn’t know when. She sat on a worn sofa in the shelter’s common room, wearing sweatpants and a thin sweater and plastic flip-flops, her face gaunt beneath tight braids. She kneaded her hands and looked into her lap as Gelernt asked her what S.’s favorite foods were, what color clothes she would like, what toys she might want to play with when they were finally together again. “Frozen,” Ms. L. whispered.

There were some creased, printed-out photos of her and S., taken before they fled Congo, spread out on a pool table at the end of the room. In one, Ms. L. smiles at the camera while S. sits behind her braiding her hair. You can recognize her in the pictures, the same softness in her eyes, the long, strong hands. But the woman in the room was, I would guess, 50 or 60 pounds thinner than the woman in the photographs. Before we said goodbye, we stood next to the pool table looking at the pictures. I remarked on how beautiful S. was, and she slowly ran a finger over her daughter in the photo, then gathered the papers up and slid them into a manila folder that she held against her chest.

The next night, after I left, they were reunited in the shelter. I’ve spoken with Gelernt several times about the moment of their reunion, what he called the most emotional thing he’d experienced in 25 years of doing immigration work. Ms. L. stood near him waiting for her daughter on a worn marble staircase just inside the shelter’s front door. When the door swung open, she crouched and stretched her arms wide. S. stepped through the doorway and saw her, and the most beautiful smile spread over the girls face, Gelernt said. She toppled forward, and Ms. L. gathered her in her arms and fell back onto the marble stairs. The look on her face as she held her daughter was almost too emotional to witness. For the next minute they lay there, clinging to each other and rocking from side to side. The only sound in the hall was a low, rhythmic moan, punctuated by S.’s higher-pitched cry.

Eventually they sat up and walked up the steps and settled on a bench in the shelter’s hallway. After a few minutes, Ms. L leaned toward S. and spoke to her in Lingala, then pointed to Gelernt, and S. stood up and walked over to him and wrapped her arms around his waist. “There are times when this work is so tiring,” Gelernt said. “But something like this, if people could only see this, I think it could change the way some of them think about these issues. This isn’t abstract policy, this is a mother and a daughter who have been through more than we can imagine. It was the rawest possible emotion,” Gelernt said.

Three days later, the immigration judge who ruled that Ms. L. would be deported denied the motion to reopen her case. “It’s horrific,” Gelernt told me. “It’s obviously going to be appealed.” As of now, they’re awaiting a decision on that appeal. Gelernt told me that S. is doing a little better, going to school in the day with some other kids in the shelter. Ms. L. remains terrified that ICE agents will show up there to take her away, or take S. away, and that she’ll be sent back to Congo and what she says and the government has agreed is certain death.