Aileen Rizo, a female math teacher, brought a claim under the Equal Pay Act ("EPA") against the Fresno County Superintendent of Schools for paying her substantially less than her male counterparts. The school district did not dispute that she was paid less and asserted that it determined her salary based on her past salary. Thus, the school district argued its actions fell under one of the EPA's affirmative defenses – that the pay disparity was due to "any other factor other than sex." After remand from the United States Supreme Court involving the judicial composition of the panel from the Ninth Circuit that had previously decided the appeal (one of the judges had died in the interim), the Ninth Circuit determined (once again) that the affirmative defense of "any other factor other than sex" was limited to job-related factors only. The Court held that an employee's prior pay is not job-related, and not a factor other than sex for EPA purposes. It held that because prior pay may carry with it the effects of sex-based pay discrimination, an employer may not rely on prior pay to meet its burden of showing that sex played no part in its pay determination.