11.8 Age Discrimination — Defense— - Bona Fide Seniority System is a legal defense to age discrimination claims. It is a system of employee rights based on length of service with a company, which allows employers to provide senior employees with additional rights and benefits and to make decisions based on their length of service. The Bona Fide Seniority System allows companies to provide employees with rights and benefits regardless of their age, so long as the system is based on the length of service and not on age. There are two types of Bona Fide Seniority Systems: Preference-Based and Non-Preference-Based. Preference-Based systems are those in which senior employees have preferential treatment over younger employees in terms of pay and benefits. Non-Preference-Based systems are those in which all employees are treated equally regardless of age, but senior employees may receive additional benefits or recognition due to their length of service.