1625.7—Differentiations based on reasonable factors other than age.
* * * 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)
No precise and unequivocal determination can be made as to the scope of the phrase “differentiation based on reasonable factors other than age.” Whether such differentiations exist must be decided on the basis of all the particular facts and circumstances surrounding each individual situation.
(c)
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.
(d)
When an employment practice, including a test, is claimed as a basis for different treatment of employees or applicants for employment on the grounds that it is a “factor other than” age, and such a practice has an adverse impact on individuals within the protected age group, it can only be justified as a business necessity. Tests which are asserted as “reasonable factors other than age” will be scrutinized in accordance with the standards set forth at part 1607 of this title.
(e)
When the exception of “a reasonable factor other than age” is raised against an individual claim of discriminatory treatment, the employer bears the burden of showing that the “reasonable factor other than age” exists factually.
(f)
A differentiation based on the average cost of employing older employees as a group is unlawful except with respect to employee benefit plans which qualify for the section 4(f)(2) exception to the Act.