The U.S. Court of Appeals for the Ninth Circuit will revisit a pay-equality ruling that federal officials and advocacy groups argued would widen and institutionalize practices that allow women to be paid less than men based on past salaries.

The en banc court is set to hear the case in December. A three-judge panel in April said pay discrepancies exclusively based on previous salary are not discriminatory under the Equal Pay Act, which forbids employers from paying women less than men. The court said an employer could base a salary on previous pay if it shows its use was “reasonable and effectuated a business policy.”

The U.S. Equal Employment Opportunity Commission called for the Ninth Circuit to rehear the case. The agency noted a split among earlier appeals court rulings and said there would be wide and harmful effects in closing the gender pay gap in the United States, where research shows women make 80 cents on the dollar compared to male counterparts.