A provision of the Fair Labor Standards Act exempts from the statute’s minimum wage and maximum hours rules “any employee employed in domestic service employment to provide companionship services for individuals who (because of age or infirmity) are unable to care for themselves (as such terms are defined and delimited by regulations of the Secretary [of Labor]).” 29 U. S. C. §213(a)(15). A Department of Labor regulation says that this statutory exemption includes those “companionship” workers who “are employed by an employer or agency other than the family or household using their services.” 29 CFR §552.109(a) (2006). P, a domestic worker who provides “companionship services” to elderly and infirm men and women, brought this lawsuit against her former employer, D. P alleged that Ds failed to pay her the minimum wages and overtime wages to which she was entitled under the FLSA and a New York statute, and she sought a judgment for those unpaid wages. The District Court found DOL’s third-party regulation valid and controlling, and it consequently dismissed P’s lawsuit. The Second Circuit found the Department’s third-party regulation “unenforceable” and set aside the District Court’s judgment. D's sought certiorari.