The Supreme Court ruled that the 20 person minimum applies ONLY to private entities. Private entities of less than 20 people that discriminate on the basis of age cannot be sued under the Age Discrimination in Employment Act. However, government entities, regardless of size, can be sued under the Act.
Here is the syllabus, which explains the case briefly:
John Guido and Dennis Rankin filed suit, alleging that the Mount Lemmon Fire District, a political subdivision in Arizona, terminated their employment as firefighters in violation of the Age Discrimination in Employment Act of 1967 (ADEA). The Fire District responded that it was too small to qualify as an “employer” under the ADEA, which provides: “The term ‘employer’ means a person engaged in an industry affecting commerce who has twenty or more employees . . . . The term also means (1) any agent of such a person, and (2) a State or political subdivision of a State . . . .” 29 U. S. C. §630(b). Initially, both Title VII of the Civil Rights Act of 1964 and the ADEA applied solely to private sector employers. In 1974, Congress amended the ADEA to cover state and local governments. A previous, 1972, amendment to Title VII added States and their subdivisions to the definition of “person[s],” specifying that those entities are engaged in an industry affecting commerce. The Title VII amendment thus subjected States and their subdivisions to liability only if they employ a threshold number of workers, currently 15. By contrast, the 1974 ADEA amendment added state and local governments directly to the definition of “employer.” The same 1974 enactment also amended the Fair Labor Standards Act (FLSA), on which many aspects of the ADEA are based, to reach all government employers regardless of their size. 29 U. S. C. §203(d), (x).
Held: The definitional provision’s two-sentence delineation, set out in §630(b), and the expression “also means” at the start of §630(b)’s second sentence, combine to establish separate categories: persons engaged in an industry affecting commerce with 20 or more employees; and States or political subdivisions with no attendant numerosity limitation.
The words “also means” in §630(b) add new categories of employers to the ADEA’s reach. First and foremost, the ordinary meaning of “also means” is additive rather than clarifying. See 859 F. 3d 1168, 1171 (case below) (quoting Webster’s New Collegiate Dictionary 34). The words “also means” occur dozens of times throughout the U. S. Code, typically carrying an additive meaning. E.g., 12 U. S. C. §1715z–1(i)(4). Furthermore, the second sentence of the ADEA’s definitional provision, §630(b), pairs States and their political subdivisions with agents, a discrete category that carries no numerical limitation.
Reading the ADEA’s definitional provision, §630(b), as written to apply to States and political subdivisions regardless of size may give the ADEA a broader reach than Title VII, but this disparity is a consequence of the different language Congress chose to employ. The better comparator for the ADEA is the FLSA, which also ranks States and political subdivisions as employers regardless of the number of employees they have. The Equal Employment Opportunity Commission has, for 30 years, interpreted the ADEA to cover political subdivisions regardless of size, and a majority of the States impose age discrimination proscriptions on political subdivisions with no numerical threshold. Pp. 4–6.
859 F. 3d 1168, affirmed.
GINSBURG, J., delivered the opinion of the Court, in which all other Members joined, except KAVANAUGH, J., who took no part in the consideration or decision of the case.