National Internal Revenue Code (NIRC)
Section 171. Authority of Internal Revenue Officer in Searching for Taxable Articles. - Any internal revenue officer may, in the discharge of his official duties, enter any house, building or place where articles subject to tax under this Title are produced or kept, or are believed by him upon reasonable grounds to be produced or kept, so far as may be necessary to examine, discover or seize the same.
He may also stop and search any vehicle or other means of transportation when upon reasonable grounds he believes that the same carries any article on which the excise tax has not been paid.