A federal judge in San Francisco found Thursday that the mass firings of probationary employees under the Trump administration were likely unlawful calling them “the lifeblood of our government.”

U.S. District Judge William Alsup instructed the Office of Personnel Management (OPM) to inform certain federal agencies that it had no authority to order the firings of probationary employees.

“The Office of Personnel Management does not have any authority whatsoever under any statute in the history of the universe to hire and fire employees at another agency,” Alsup said per The Washington Post. “They can hire and fire their own employees.”

The ruling is in response to a lawsuit filed by unions and nonprofit organizations led by the American Federation of Government Employees pushing back against the administration’s efforts to shrink the workforce that Trump has called bloated and impediment to his agenda.