The District’s labor-management relations board has upheld an arbitrator’s decision ordering the D.C. Public Schools to rehire 75 new teachers fired in 2008 by then-Schools Chancellor Michelle A. Rhee.

The Public Employee Relations Board, which rules on disputes between city agencies and labor unions, said in a Sept. 15 decision that arbitrator Charles Feigenbaum acted appropriately in February when he ordered the teachers reinstated with back pay, which could total as much as $7.5 million.

Feigenbaum said the dismissals were improper because the teachers, who were in their two-year probationary period, were not told why they were let go. He called it the “glaring and fatal flaw” in Rhee’s action.

The 75 teachers were among the approximately 1,000 educators terminated during Rhee’s 31 / 2-year tenure, which ended with her resignation last fall. She considered the dismissals a priority in her effort to upgrade the quality of teaching in the system.

These dismissals predate the 2009 launch of the IMPACT evaluation system, under which all teachers are subject to dismissal or a one-year grace period if they receive poor ratings.

The District argued that the arbitrator acted outside his authority and that the school system had the right to fire the teachers during probation because they had received negative recommendations from their principals.

The city could continue to appeal the case to the D.C. Superior Court and D.C. Court of Appeals. Schools spokesman Hassan Charles said Thursday that the school system’s attorneys are discussing the options.

Washington Teachers’ Union President Nathan Saunders ­noted that the standard for overturning an arbitrator’s decision is difficult to meet and said that if the city does decide to appeal, it is likely in an effort to delay the reinstatements as long as possible.

“It is time to stop stalling and put good teachers back to work with deserving students and parents,” Saunders said.

The negative recommendations from the principals, excerpted by the arbitrator, include one teacher who was late 24 times and had 20 days of absences after returning from two months of sick leave. After the initial leave, most of the absences were on Mondays and Fridays, the arbitrator’s decision said.

Another teacher received warnings from his principal about playing movie DVDs and gospel songs during class time, as well as using inappropriate language with students. One teacher had poor classroom management skills and had been AWOL for the final two months of the 2007-08 school year.

Probationary employees generally have fewer job protections than those with permanent status. But the union’s contract with the city at the time made no distinction between probationary and tenured teachers. The arbitrator said they were denied the due process accorded to tenured teachers.