The U.S. Supreme Court unanimously confirmed on Tuesday that the protections against age discrimination in the federal Age Discrimination in Employment Act of 1967 (ADEA) apply to all state and local government employers regardless of their number of employees.

The Supreme Court's decision in Mount Lemmon Fire District v. Guido, Case No. 17-587 (Nov. 6, 2018), affirmed the U.S. Court of Appeals for the Ninth Circuit's ruling and resolved a split among circuit courts by confirming that, although the ADEA applies to private sector employers only if they employ 20 or more persons, state and local governments are a separate category with no minimum employee requirement.

The Ninth Circuit's analysis was that the ADEA creates different categories of employers for coverage purposes. The Supreme Court affirmed that analysis. The ADEA defines "employer" as "a person engaged in an industry affecting commerce who has twenty or more employees," but states that the term "also means (1) any agent of such a person, and (2) a State or political subdivision of a State and any agency or instrumentality of a state or a political subdivision of a State, and any interstate agency..." 29 U.S.C. §630(b). The Supreme Court agreed with the Ninth Circuit that the use of the phrase "also means" places state and local government employers into a separate category under the ADEA from private sector employers who are subject to the 20-employee threshold.

The Supreme Court noted that the wording of the ADEA definition of "employer" was distinct from Title VII's definition of employer, where state and local government employers are subject to the same 15-employee threshold as private sector employers.

The 8-0 ruling in Guido (newly appointed Justice Brett Kavanaugh did not participate) resolves the Ninth Circuit's split with the Sixth, Seventh, Eighth and Tenth Circuits, each of which held that the 20-employee threshold under the ADEA applied to state and local government employers.

In light of the Guido decision, state and local government employers with fewer than 20 employees will need to be prepared to defend new claims under the ADEA.