Los Angeles-based US District Court judge Dolly M. Gee ruled on Monday that migrant families detained after crossing the US-Mexico border cannot be held in long-term detention, according to The New York Times.

Instead, the government will have to abide by a policy known as the Flores agreement, which mandates that children have to be released after 20 days of detention. The migrants and asylum seekers then either have to be directly deported back to their home countries if a court proceeding has already occurred; released into US communities, where they will await future court dates; or get permission from their parents to be detained for longer, which seems unlikely, Politico reports.

Since the Trump administration has vowed to stop separating families, it’s possible that the parents of children will also be released from detention after 20 days, Politico notes.

Take Action: Reunite All Separated Families and Support Foreign Aid to End the Root Cause of the Migration Crisis

The Justice Department, however, said in a statement that the ruling means more family separations will happen.

“We disagree with the court’s ruling declining to amend the Flores Agreement to recognize the current crisis of families making the dangerous and unlawful journey across our southern border,” the department wrote in a statement, according to the Times. “But the court does appear to acknowledge that parents who cross the border will not be released and must choose between remaining in family custody with their children pending immigration proceedings or requesting separation from their children so the child may be placed with a sponsor.”

Human rights organizations, meanwhile, argue that Gee’s decision forces the government to stop separating families.

“The court clearly finds that the attorney general’s efforts to strip detained immigrant children of their fundamental rights were completely unfounded and based on an intentional misreading of the 1997 Flores agreement,” Peter Schey, president of the Center for Human Rights and Constitutional Law, told the Times.

Read More: One Simple Way to Stop the Migration Crisis at US Borders

Either way, the ruling complicates the Trump administration’s attempt to end “catch-and-release,” through which detained migrants and asylum seekers are detained, released, and then expected to show up to court dates.

It also reflects the untenable nature of the administration's “zero tolerance” policy, which has been curtailed in courts and heavily criticized since it was enacted earlier this year.

This latest setback comes after lawyers for the administration had tried to amend the Flores agreement to secure the right to detain migrants indefinitely, and to establish unlicensed detention centers for children.

Read More: Federal Judge Orders Trump to Reunite Migrant Families Within 30 Days

Judge Gee flatly rejected both proposals.

"Defendants seek to light a match to the Flores Agreement and ask this Court to upend the parties’ agreement by judicial fiat," wrote Gee. "It is apparent that Defendants’ Application is a cynical attempt ... to shift responsibility to the Judiciary for over 20 years of Congressional inaction and ill-considered Executive action that have led to the current stalemate."

Gee noted that the Obama administration was blocked from amending the Flores agreement for similar purposes in 2015, and that the Trump administration had failed to offer novel arguments.

Now the government will likely have to further alter its immigration enforcement priorities, Al Jazeera reports.

Read More: This Immigrant Mother Is Still Waiting to See Her 3 Children

Administration officials are currently working to fulfill another court order calling on all migrant families to be reunited and have so far missed the first deadline of locating and returning children under the age of 5, according to NPR.

It's extremely disappointing the government will not be in full compliance with the court order by tomorrow, but the most important thing is that the court will continue to hold the administration's feet to the fire to get these kids reunited with their parents.

— ACLU (@ACLU) July 9, 2018

Gee said that the administration, rather than doubling down on their past policies, could reconsider their hardline approach to immigration.

"Absolutely nothing prevents Defendants from reconsidering their current blanket policy of family detention and reinstating prosecutorial discretion," Gee wrote.