In Prill v. NLRB, 755 F.2d 941, 948 (D.C. Cir. 1985), the D.C. Circuit remanded a case to the agency because "a regulation [was] based on an incorrect view of applicable law."
Interpreting similar language in 29 C.F.R. § 101.10 as meaning "that the Board's procedures are to be controlled by the Federal Rules of Civil Procedure as far as practicable" (cleaned up)