27 C.F.R. § 22.121 – Liability and responsibility of carriers.

(a) A person or carrier transporting tax-free alcohol to a consignee or returning the alcohol to the consignor is responsible for the safe delivery and is accountable for any tax-free alcohol not delivered.
(b) A person or carrier transporting tax-free alcohol in violation of any law or regulation pertaining thereto, is subject to all provisions of law relating to alcohol subject to and the payment of tax thereon, and shall be required to pay the tax.
(Sec. 201, Pub. L. 85-859, 72 Stat. 1314, as amended (26 U.S.C 5001))