CNN  — 

Potentially thousands more parents and children the US government split up at the southern border will now be included in a lawsuit over family separations, a judge ruled Friday.

US District Judge Dana Sabraw’s 14-page ruling is a major blow to the Trump administration, which had argued that a new group of separated families revealed in a government watchdog report shouldn’t be included in the case. The report from the Health and Human Services inspector general had found that thousands more children had been separated than previously acknowledged.

As a result of the judge’s order, officials may have to comb through a massive trove of case files and pinpoint exactly how many families were separated going back as far as July 1, 2017. HHS and the inspector general’s office were unable to identify exactly how many more families were separated because there were “significant challenges in identifying separated children.” Officials estimated that the children were separated, received by HHS for care and released prior to Sabraw’s June 26, 2018, court order ordering a halt to most family separations at the US border.

“The hallmark of a civilized society is measured by how it treats its people and those within its borders,” wrote Sabraw, who sits in the Southern District of California. “That Defendants may have to change course and undertake additional effort to address these issues does not render modification of the class definition unfair; it only serves to underscore the unquestionable importance of the effort and why it is necessary (and worthwhile).”

The Ms. L et al. vs. Immigration and Customs Enforcement et al. case was initially prompted by the separation of a Congolese woman and her 7-year-old daughter. The American Civil Liberties Union originally filed the case last year and it was later expanded to become a class action lawsuit.

Last June, Sabraw issued a preliminary injunction blocking most family separations at the US-Mexico border and ordered the government to reunite the families it had divided.

Since then, the administration has provided regular reports to the court on the reunification status of children and parents whom the government separated, including some parents who were deported but ultimately elected not to be reunified with their children. As of March 4, 2,741 of 2,816 children have been discharged from government care.

But recent revelations have raised more questions about when separations began taking place and how many more families were separated.

Following the HHS IG report, plaintiffs in the Ms. L case requested that the scope be clarified to include those children.

Sabraw cited the IG report in his order. “Clearly, the OIG Report is a significant development in this case,” he wrote. The class is modified to include separations that occurred as far back as July 1, 2017.

Last month, Sabraw pressed government lawyers over whether the administration should be required to identify those children and parents separated. “The fundamental premise of the lawsuit is that there’s an unlawful separation practice initiated by this administration,” Sabraw said.

“The June 26 date is completely arbitrary viewed in that light,” he added, referring to the date when he issued a preliminary injunction.

Government lawyers pushed back, defending their work to identify and reunify families, and emphasizing what a significant undertaking it would be for the administration to compile a new list.

In a declaration previously submitted to the court, Jallyn N. Sualog, the deputy director for Children’s Programs for the Office of Refugee Resettlement, wrote it would take up to 376,664 hours to comb through 47,083 files of children who were in ORR custody between July 1, 2017 and June 25, 2018. Put another way, the official said, it would take 100 analysts working eight hours a day up to 471 consecutive calendar days to even begin pinning down the details.

Sabraw acknowledged the weight of the task in the order, but added “it clearly can be done.”

Lee Gelernt, lead attorney in the lawsuit and deputy director of the ACLU’s Immigrants’ Rights Project, responded to the order late Friday.

“The court made clear that potentially thousands of children’s lives are at stake and that the Trump administration cannot simply ignore the devastation it has caused,” he said in a statement.