sentences:  It held that the Secretary was required to show that Congress had authorized the regulation either by an express delegation or by implied approval of a "substantial and consistent" administrative practice, citing "Zemel v. Rusk" (1965).The court found no express statutory authority for the revocation.The Court of Appeals took note of the Secretary's reliance on "a series of statutes, regulations, proclamations, orders and advisory opinions dating back to 1856," but declined to consider those authorities, reasoning that "the criterion for establishing congressional assent by inaction is the actual imposition of sanctions and not the mere assertion of power."