Cathy Harris, chairwoman of the Merit Systems Protection Board, said in the order that evidence presented by the Office of Special Counsel (OSC) indicated the department illegally fired some 5,950 workers on probationary status, or newer employees.
Harris said the USDA must reinstate the workers, in an order that is to remain in effect through April 18.
The USDA has not responded to requests for comment.
Harris was granting a request from the OSC, which asked for a stay while it continues to investigate the mass terminations.
The position was reached after reviewing evidence and interviewing multiple USDA officials.
The terminations happened only because officials determined that the workers were in positions that were not mission-critical, the OSC said in the filing to the Merit Systems Protection Board.
The USDA sent identical letters to all of the terminated probationary workers, stating that the termination was based on their performance, but the letters did not explain how the performance was deficient, according to the watchdog. USDA officials told the OSC that they drafted the templates used to execute the mass terminations.
Officials said the mass terminations were prompted by Office of Personnel Management guidance on probationary workers, including a directive to fire employees who were not considered mission-critical.
The OSC said it believed that the USDA terminated the workers in violation of federal law, which states in part that workers shall be protected from “arbitrary action, personal favoritism, or coercion for partisan political purposes.”
During the stay, the OSC would further investigate the matter.
The Merit Systems Protection Board, which handles federal staffing disputes, on March 3 ordered the OSC to provide the names of the employees who were fired. The office said it complied with the order.