27 C.F.R. § 19.358 – Cases.

(a) On completion of bottling, a proprietor must place filled bottles with properly affixed closures in cases. A proprietor may only fill cases with the same kind, size, and proof of spirits. Normally, the cases must be sealed; however, cases may be temporarily retained on bonded premises without being sealed pending the affixing to bottles of any required labels, State stamps, or seals. Unsealed cases must be marked in accordance with subpart S of this part, and segregated from other cases until sealed. All cases must be sealed and marked as provided in subpart S of this part before removal from the bonded premises.
(b) Filled bottles may remain on the bottling line at the end of the workday if the identical product will be bottled on the next bottling shift and if adequate security measures are in place to prevent theft.
(26 U.S.C. 5201, 5206)