27 CFR 19.11: Right of entry and examination.

A TTB officer may enter any distilled spirits plant, any other premises where distilled spirits operations are carried on, or any structure or place used in connection with distilled spirits operations, at any time of day or night. A TTB officer may examine materials, equipment, and facilities, and make any gauges and inventories. Whenever a TTB officer states his or her name and office and demands admittance but is not admitted into the premises or place, the TTB officer is authorized to use all necessary force to gain entry.