A federal judge on Thursday ordered the Office of Personnel Management to rescind earlier instructions telling federal agencies to "promptly determine whether these employees should be retained at the agency."

The directions, communicated in a Jan. 20 memo and Feb. 14 internal email, are "illegal" and "should be stopped, rescinded," Judge William Alsup of the Northern District of California said from the bench.

The ruling does not reinstate dismissed employees.

The judge instructed the Office of Personnel Management to communicate to the Department of Defense on Friday — ahead of expected probationary terminations — that he has ruled they are invalid.

Alsup has also ordered a hearing scheduled in which acting Office of Personnel Management Director Charles Ezell will testify. The timing of that hearing is unclear.

"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 within another agency," Alsup said Thursday night. "It can hire its own employees, yes. Can fire them. But it cannot order or direct some other agency to do so."

"OPM has no authority to tell any agency in the United States government, other than itself, who they can hire and who they can fire, period. So on the merits, I think, we start with that important proposition," he said.

Alsup called probationary employees "the lifeblood of our government."

"They come in at the low level and they work their way up, and that's how we renew ourselves and reinvent ourselves," he said.

"The government's position, for the first time in history of the United States, is that these employees can be fired at will," an attorney for the plaintiffs, Danielle Leonard, said. "That is not the law, Your Honor. Probationary employees and agencies do have obligations before firing probationary employees."

"The government should not operate in secrecy when it comes to wholesale orders to fire so many people," Leonard pleaded with the court.

There was significant disagreement as to whether the OPM's phone call to agencies instructing the firing of probationary employees in mid-February was an "order" or a "request."

"Something aberrational happens, not just in one agency, but all across the government, in many agencies on the same day, the same thing. Doesn't that sound like to you that somebody ordered it to happen, as opposed to, 'Oh, we just got guidance,'" Alsup posited to local Assistant U.S. Attorney Kelsey Helland, who was the only representative of the government at the hearing.

"An order is not usually phrased as a request," Helland said. "Asking is not ordering to do something."

Helland suggested impacted employees should go through the Office of Special Counsel or the Merit Systems Protection Board to fight their employment status — and that a temporary restraining order like this would be unnecessary.

"Are they really contending to this court that all of these federal employees are lying, Your Honor?" Leonard asked. "That's what counsel is saying. I don't think it's credible."

Hundreds of thousands of people could have been affected by the directives from the Trump administration, according to data from OPM, although the exact number of people who were terminated was not immediately clear.