Opinion of the Court
“rare bird[s]” occupy both civilian and military roles. Babcock v. Kijakazi, 595 U. S. ___, ___ (2022) (slip op., at 2). They serve as “civilian employee[s]” engaged in “organizing, administering, instructing,” “training,” or “maintenance and repair of supplies” to assist the National Guard. 10 U. S. C. §10216(a)(1)(C); see 32 U. S. C. §§709(a)(1)–(2); Babcock, 595 U. S., at ___ (slip op., at 2). Yet, they must “as a condition of that employment … maintain membership in the [National Guard]” and wear a uniform while working. 10 U. S. C. §10216(a)(1)(B); see 32 U. S. C. §§709(b)(2)–(4). Except when participating as National Guard members in part-time drills, training, or active-duty deployment, see 32 U. S. C. §§502(a) and 709(g)(2), dual-status technicians work full time in a civilian capacity and receive federal civil-service pay. See Babcock, 595 U. S., at ___–___ (slip op., at 2–3); see also 5 U. S. C. §2101(a).
Importantly, under the Technicians Act of 1968, each dual-status technician is considered “an employee of the Department of the Army or the Department of the Air Force, as the case may be, and an employee of the United States.” 32 U. S. C. §709(e). While it is state adjutants general who “employ and administer” dual-status technicians working for their respective State National Guard units, they can only do so pursuant to an express “designat[ion]” of authority by the Secretary of the Army or the Secretary of the Air Force. §709(d); see also Dept. of the Army, S. Resor, Delegation of Authority Under the National Guard Technicians Act of 1968 (General Order 85, Dec. 31, 1968) (General Order 85) (current order designating the relevant authority).
B
The parties’ collective-bargaining relationship dates back to 1971, when the Guard recognized the Union as the exclusive representative of its dual-status technicians. They have since negotiated a number of collective-bargaining
