26 USC 5203 - Entry and examination of premises

(a) Keeping premises accessible 
Every proprietor of a distilled spirits plant shall furnish the Secretary such keys as may be required for internal revenue officers to gain access to the premises and any structures thereon, and such premises shall always be kept accessible to any officer having such keys.
(b) Right of entry and examination 
It shall be lawful for any internal revenue officer at all times, as well by night as by day, to enter any distilled spirits plant, or any other premises where distilled spirits operations are carried on, or structure or place used in connection therewith for storage or other purposes; to make examination of the materials, equipment, and facilities thereon; and make such gauges and inventories as he deems necessary. Whenever any officer, having demanded admittance, and having declared his name and office, is not admitted into such premises by the proprietor or other person having charge thereof, it shall be lawful for such officer, at all times, as well by night as by day, to use such force as is necessary for him to gain entry to such premises.
(c) Furnishing facilities and assistance 
On the demand of any internal revenue officer or agent, every proprietor of a distilled spirits plant shall furnish the necessary facilities and assistance to enable the officer or agent to gauge the spirits in any container or to examine any apparatus, equipment, containers, or materials on such premises. Such proprietor shall also, on demand of such officer or agent, open all doors, and open for examination all boxes, packages, and all casks, barrels, and other vessels on such premises.
(d) Authority to break up grounds or walls 
It shall be lawful for any internal revenue officer, and any person acting in his aid, to break up the ground on any part of a distilled spirits plant or any other premises where distilled spirits operations are carried on, or any ground adjoining or near to such plant or premises, or any wall or partition thereof, or belonging thereto, or other place, to search for any pipe, cock, private conveyance, or utensil; and, upon finding any such pipe or conveyance leading therefrom or thereto, to break up any ground, house, wall, or other place through or into which such pipe or other conveyance leads, and to break or cut away such pipe or other conveyance, and turn any cock, or to examine whether such pipe or other conveyance conveys or conceals any distilled spirits, mash, wort, or beer, or other liquor, from the sight or view of the officer, so as to prevent or hinder him from taking a true account thereof.
(e) Penalty 
For penalty for violation of this section, see section 5687.