In the case of Kentucky Retirement Systems v. Equal Employment Opportunity Commission (2007), the U.S. Supreme Court ruled in favor of a retirement system that had been accused of age discrimination. The Equal Employment Opportunity Commission (EEOC) claimed that Kentucky's retirement plan was discriminatory because it used an employee’s age as a factor to determine eligibility for disability retirement benefits, which were more generous than normal retirement benefits. However, the court held 5-4 that while Kentucky's system did use age as a factor, it was not intended or used to harm older workers but rather to maintain pension equity among all employees regardless if they retire normally or due to disability before reaching normal retirement age. Therefore, this practice did not violate the Age Discrimination in Employment Act (ADEA). This ruling clarified how courts should interpret and apply ADEA when considering whether state policies are discriminatory based on their impact on older workers.

In the dissenting opinion for KY. RET. SYS. v. EEOC, Justice Breyer argued that Kentucky's retirement system was discriminatory and violated the Age Discrimination in Employment Act (ADEA). He disagreed with the majority's view that there was no discrimination because all employees were subject to the same rules regardless of age; instead, he believed that these rules had a disparate impact on older workers who decided to continue working past normal retirement age as they would receive lower pension benefits compared to younger workers who worked for an equivalent period of time or made similar contributions into their pensions. Furthermore, Justice Breyer contended that this case should not be dismissed at such an early stage without allowing further investigation into whether Kentucky could justify its policy under ADEA’s “reasonable factors other than age” defense.