The federal Equal Opportunity Commission is appealing a court ruling that absolved Baltimore County of having to return money to thousands of employees who overpaid into the pension system.

The commission filed notice of its appeal last week. It did not describe the reasons for the appeal, and a spokesman declined to comment.

EEOC lawyers have argued that the county knew for years that its age-based pension plan rates were discriminatory, and the possibility of having to pay employees back should have been “foreseeable for several decades.”

A federal judge ruled in 2012 that the county had been wrong to overcharge older workers. In August, another judge ruled the county would not have to pay those workers back.

Officials estimated that the county could have been on the hook for as much as $19 million in potential payments to the workers.

It's not clear how many workers would have been due a repayment. The county has said it would have taken years of research to figure out how many workers were affected and how much money each was owed.

The case largely affects workers hired before 2007, when the county ended its decades-long practice of setting pension contribution rates for new hires based on age.

The allegations of unfairness were first brought to light in 1999 and 2000, when two correctional officers filed complaints through the EEOC.

The EEOC didn't sue on the workers' behalf until 2007, which U.S. District Judge Richard D. Bennett said was an “unreasonable delay” that was a factor in his decision not to award damages.

Bennett noted that monetary damages haven't been awarded in similar pension cases and that damages aren't required under the law that's central to this case, the federal Age Discrimination in Employment Act.

The appeal will be considered at the 4th U.S. Circuit Court of Appeals in Richmond, Va.

“We believe that the trial court issued the correct decision,” county spokeswoman Ellen Kobler said.

pwood@baltsun.com

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