The board overseeing federal government employment temporarily blocked the firing of six government workers on Tuesday after finding that their dismissal, part of the mass purge of probationary government employees by Elon Musk’s Department of Government Efficiency, likely was illegal.

The decision from the Merit Systems Protection Board requires the government to give the six workers their jobs back with back pay for 45 days while the Office of Special Counsel, the agency that oversees government employment complaints, further investigates their removal. In doing so, the board determined that “there are reasonable grounds to believe that each of the six agencies engaged in a prohibited personnel practice,” as the firings did not relate to the employees’ performance. The order follows an Office of Special Counsel decision that itself found the firings likely were illegal and had sent the issue to the Merit System Protection Board for a definitive ruling.

The board’s decision could have sweeping consequences for the tens of thousands of probationary government workers caught up in Musk’s mass purge of the federal workforce. The way the six workers in this case were fired is identical to most of those purged by Musk in recent weeks.

After the board’s ruling, Office of Special Counsel head Hampton Dellinger called on agencies to immediately reverse any illegal dismissal while he pursues ways to allow these fired government workers to challenge their dismissals in a class action.

“I am very grateful the MSPB has agreed to postpone these six terminations,” Dellinger said in a statement. “These stays represent a small sample of all the probationary employees who have been fired recently so our work is far from done. Agency leaders should know that OSC will continue to pursue allegations of unlawful personnel actions, which can include asking MSPB for relief for a broader group of fired probationary employees. I urge agency leaders to voluntarily and immediately rescind any and every unlawful termination of probationary employees.”

The probationary period for government workers usually covers the first year of employment for new hires or workers who either have been promoted or moved to a new agency. Probationary workers have fewer civil service protections but not none at all. The probationary period is meant to be used for performance evaluation, not as a punishment or to target firings for other reasons.

In his Feb. 21 ruling, Dellinger wrote that “the Agencies improperly circumvented [reduction in force] regulations by terminating Complainants and other probationary employees en masse without regard to each employee’s individual performance for the purpose of restructuring government agencies and reducing costs.”

That is likely to be true for the vast majority of probationary workers fired as part of Musk’s mass purge. An amended complaint from Democracy Forward Foundation, the liberal nonprofit organization that brought the six workers’ complaints before the Office of Special Counsel, filed the day after Dellinger’s decision expands the number of fired workers whose terminations were similar to the six workers.

“Data we have compiled from over 2,000 terminated probationary employees, including termination letters and affidavits from representative employees, reflects a clear pattern — agencies, acting at OPM’s direction, are committing widespread prohibited personnel practices,” the amended complaint to the Office of Special Counsel states.

The complaint alleges that “agencies terminated employees … via the same processes and letters across organizational lines,” with little mention of performance. Where employee performance was mentioned, the complaint states that “this justification is pretextual,” because “[t]hese employees universally received accolades for performance, promotions, and awards within as little as two weeks prior to their terminations.”

Democracy Forward Foundation has called on Dellinger to expand his ruling for the six workers to cover “all similarly situated probationary employees.”