* * * it shall not be unlawful for an employer, employment agency, or labor organization * * * to take any action otherwise prohibited under paragraphs (a), (b), (c), or (e) of this section * * * where the differentiation is based on reasonable factors other than age * * *.(b) When an employment practice uses age as a limiting criterion, the defense that the practice is justified by a reasonable factor other than age is unavailable.
(c) Any employment practice that adversely affects individuals within the protected age group on the basis of older age is discriminatory unless the practice is justified by a “reasonable factor other than age.” An individual challenging the allegedly unlawful practice is responsible for isolating and identifying the specific employment practice that allegedly causes any observed statistical disparities.
(d) Whenever the “reasonable factors other than age” defense is raised, the employer bears the burdens of production and persuasion to demonstrate the defense. The “reasonable factors other than age” provision is not available as a defense to a claim of disparate treatment.
(e)
(2) Considerations that are relevant to whether a practice is based on a reasonable factor other than age include, but are not limited to:
(ii) The extent to which the employer defined the factor accurately and applied the factor fairly and accurately, including the extent to which managers and supervisors were given guidance or training about how to apply the factor and avoid discrimination;
(iii) The extent to which the employer limited supervisors' discretion to assess employees subjectively, particularly where the criteria that the supervisors were asked to evaluate are known to be subject to negative age-based stereotypes;
(iv) The extent to which the employer assessed the adverse impact of its employment practice on older workers; and
(v) The degree of the harm to individuals within the protected age group, in terms of both the extent of injury and the numbers of persons adversely affected, and the extent to which the employer took steps to reduce the harm, in light of the burden of undertaking such steps.
