Employers should not be allowed to use a job applicant's prior salary to justify paying male and female employees differently for the same work, a lawyer for a California schools professional said Friday, urging the U.S. Court of Appeals for the Ninth Circuit to adopt a ruling the court issued last year.

That earlier Ninth Circuit decision would have stopped employers from using compensation history alone or in combination with other factors to defend disparities between male and female employees. But the U.S. Supreme Court in February vacated the decision after concluding the decisive vote of a judge who died about two weeks before the ruling was issued should not have counted.

The Supreme Court did not confront the merits of the case, Rizo v. Yovino, which tests the scope of the federal Equal Pay Act. The Ninth Circuit, sitting en banc, now is weighing its next steps, and both sides in the dispute offered competing views Friday about what the appeals court should do now. The dispute has attracted widespread attention from business interests and advocates for workers.

Daniel Siegel, the attorney for Aileen Rizo, a math consultant who alleged Fresno County schools had paid her $10,000 less than male colleagues, argued Friday that the 11 judges of the Ninth Circuit en banc panel should not disturb the earlier decision favoring his client.

That divided en banc ruling, published in April 2018, was written by the late Judge Stephen Reinhardt, long considered the "liberal lion" of the Ninth Circuit. Judge Carlos Bea has been picked to replace Reinhardt on the en banc court presiding over Rizo's claims. The court has not yet said whether it will order new briefing or hold a new oral argument.

"Allowing an employer to consider prior salary along with other factors in setting an employee's initial salary might mitigate but does not eliminate the discriminatory impact of past employment practices," Siegel told the appeals court. "Even if prior salary is valued at just 10% or less in an employer's assessment of the various factors to be considered in setting a new employee's compensation, it still brings a discriminatory factor into the equation."

Siegel called Rizo's situation "a powerful rebuttal to the claim that prior salary alone can legitimately explain why a female worker is being paid less than her male colleagues." He continued: "Ms. Rizo had better qualifications and more experience than her male comparators. Nonetheless, the county started her salary at over $10,000 lower than the salary it gave them."

Lawyers for Jim Yovino, the Fresno County superintendent of schools, on Friday countered Siegel's argument that the en banc appeals court adopt the prior ruling. Yovino's attorneys at Jones Day argued in their court filing the en banc Ninth Circuit "must decide this case afresh, with a full complement of living judges."

Since the en banc Ninth Circuit issued its ruling last year in favor of Rizo, another federal appeals court, based in Richmond, Virginia, ruled employers can rely on a job candidate's prior salary history to justify a pay disparity, Jones Day partner Shay Dvoretzky said in Friday's filing.

The Fourth Circuit's decision upheld a ruling against a university professor who argued she was unlawfully being paid less than male colleagues for the same work. The appeals court determined the university had shown the salary disparity was based on a "factor other than sex." Two male colleagues were making more based on their salaries as administrators.

"Because Rizo's pay disparity stemmed from differences between her and her colleagues' prior pay, it was based on a 'factor other than sex.' As a result, the superintendent cannot be held liable under the Equal Pay Act for that disparity," Dvoretzky said.

Reinhardt had "fully participated in the original Rizo ruling before he died in March 2018, the appeals court said last year. The majority decision and concurrences were final, and the voting complete, at the time he died. Still, the Supreme Court said the Ninth Circuit was wrong to consider his vote.

"That practice effectively allowed a deceased judge to exercise the judicial power of the United States after his death," the Supreme Court said in its unsigned decision. "But federal judges are appointed for life, not for eternity."