(NewsNation) — While the Biden administration has reunited 500 immigrant children with their families who were separated under the Trump administration, a lawyer for the American Civil Liberties Union (ACLU) says they don’t intend to stop until every child is reunited with their parents.

Lee Gelernt, an attorney and deputy director with the ACLU’s Immigrants Rights Project, said there are still many families whom they haven’t been able to reach.

“When we contacted [the separated families] the first time, it was during the Trump administration, and the Trump administration was not willing to bring them back and reunify them,” Gelernt said.

The ACLU hopes to be able to reunite another “200 to 300” migrants in the next couple of months. Beyond that, however, they don’t know how long it will take to reunite every family that was separated under the Trump administration’s Zero Tolerance Policy at the U.S.-Mexico border.

Regardless of the national politics and rhetoric surrounding issues at the southern border, Gelernt believes family separation should never have been an option on the table.

“Let’s do the work to have a more efficient and fair process at the border for asylum seekers,” he said. “But let’s never go anywhere near again using little babies and toddlers as pawns.”