paraphrase The statutory language of the ADEA recognizes that age might be an appropriate basis for an employment decision if consideration of age is necessary to observe the terms of a bona fide seniority system. The Supreme Court has reinforced this permissibility provided the seniority system is not designed to produce the discriminatory result.9 Seniority is a measure of an employee's years of service with an employer, and a bona fide seniority system uses this length of service to determine the appropriate benefit level for the employee