27 C.F.R. § 19.13
(a) General. TTB may assign TTB officers to a distilled spirits plant and utilize controls, such as Government locks and seals, if TTB decides that those measures are necessary to effectively supervise the operations. If TTB decides that such supervision is necessary:
(b) Notification of supervision. If TTB determines that supervision of plant operations is necessary, TTB will notify the proprietor of the extent to which TTB intends to supervise those operations. If TTB determines later that TTB supervision is no longer necessary, the appropriate TTB officer will notify the proprietor of that fact.
(26 U.S.C. 5201, 5202, 5553)