PHOENIX >> The Trump administration says a ruling this week by a federal judge in San Diego requiring the government to reunify families separated at the border means authorities can legally keep families detained until their cases are complete.

The interpretation means immigrant families could spend months or even years in detention — even those seeking asylum — because of a years-long backlog in immigration court.

The Justice Department has said cases in which immigrants remain detained move through the system quicker than if they are released, but the backlog is still thousands of cases deep.

The Department of Justice said in a court filing today that a case known as the Flores agreement allows the government to detain families now that the California judge has barred their separation.

“The Trump Administration has been engaged — since January of 2017 —in restoring order to the lawlessness at the Southwest border and protecting our nation’s citizens, but we are beholden to a broken immigration system that Congress has refused to fix and that courts have exacerbated,” the department said in a news release.

The Flores agreement is a long-standing guide as to how and how long the government can detain immigrant children. It stems from a lawsuit filed in 1985 by an immigrant girl, Jenny Lisette Flores, who was detained by immigration authorities in poor conditions and who was not allowed to be released to an aunt.

The Flores agreement requires the government to release children from immigration detention “without unnecessary delay,” which the government has generally interpreted to mean about 20 days.

But the DOJ is zeroing in on the requirement, saying that the order this week from U.S. District Court Judge Dana Sabraw requires that children’s release be delayed so that they can stay with their parents.

Sabraw set a 30-day deadline for reuniting parents and children and called for young children to be reunited more quickly.

The administration has long-argued that releasing asylum-seekers who cross the border illegally amounts to catch-and-release and results in many not showing up for their court hearings.

The administration says it is enforcing a zero-tolerance policy requiring border agents to arrest and prosecute anyone caught crossing the border illegally. That resulted in more than 2,000 children being separated from their parents.