John Moore/Getty Images An emotional father embraces his son for the first time in months on Aug. 7, 2018, in Guatemala City, after nine children were flown from New York to reunite with their families.

A federal judge ruled Friday that the Trump administration may have to reunite potentially thousands of more families who were separated before the “zero tolerance” policy on immigration was implemented last April.

It’s the latest development in the ACLU’s family separation case against U.S. Immigration and Customs Enforcement. The class-action lawsuit had been restricted to the 2,816 children listed as being in the Office of Refugee Resettlement’s custody as of June 26, when U.S. District Judge Dana Sabraw issued an injunction to halt the “zero tolerance” policy that led to criminal processing of border crossers.

“We’re thrilled the court has recognized the importance of finding these potentially thousands of additional separated families,” said Lee Gelernt, the lead lawyer on the American Civil Liberties Union’s case, “and we intend to do everything we can to locate them as soon as possible.”

ICE did not immediately respond to HuffPost’s request for comment.

Currently most of the children separated under “zero tolerance” have been released from ORR custody to either their parents, a family sponsor or a foster family. But since January, when an internal watchdog report stated that there were thousands of more parents who could have been separated from their children, the ACLU has argued that these families should also be included in the litigation.

“A case always takes into account further developments,” said Gelernt, during a recent hearing for the case. “This one is a bombshell that no one could’ve really anticipated.”

The government has resisted the idea of expanding the class, saying it would be too much of a “burden” to reunite these families since they had no formal tracking system in place. The deputy director of ORR said analysts would have to work eight hours a day for up to 15 months to “even begin reconciling” data on separated families.

But advocates say the Trump administration has a responsibility to reunite the families it tore apart, regardless of how much work it would take.

“I think the policy of taking the children away in the first place was cruel,” said Gelernt in a recent interview, “but to not even have a system to return the parents to the children just increases the magnitude of the cruelty.”

Sabraw didn’t immediately outline what exact steps the government must take to account for the additional separated families who are now part of the lawsuit.