In Johnston-Willis Ltd. v. Kenley, 6 Va. App. 231, 243, 369 S.E.2d 1, 7 (1988), we defined "the appropriate standard of review in terms of the degree of deference to be given to agency decisions." We stated: Agency findings of fact are to be accorded great deference under the substantial evidence standard of review. However, when deciding whether an agency has followed proper procedures or complied with statutory authority . . ., an inquiry into whether there is substantial evidence in the record to support findings of fact of an agency is wholly inappropriate. Indeed, even though an agency's findings of fact may be supported by substantial evidence in the record, it may be subject to reversal because the agency failed to observe required procedures or to comply with statutory authority. See, e.g., Atkinson v. Virginia Alcoholic Beverage Control Commission, 1 Va. App. 172, 336 S.E.2d 527 (1985). Thus, where the legal issues require a determination by the reviewing court whether an agency has, for example, accorded constitutional rights, failed to comply with statutory authority, or failed to observe required procedures, less deference is required and the reviewing courts should not abdicate their judicial function and merely rubber-stamp an agency determination. Johnston-Willis, 6 Va. App. at 243, 369 S.E.2d at 7-8. However, when the question requires an interpretation that is "within specialized competence of the agency," the agency's decision is afforded special deference. Id. at 244, 369 S.E.2d at 8.