19 U.S.C. § 460
Under regulations prescribed by the Secretary of the Treasury, any imported distilled spirits, wines, or other liquors which may be in any customs bonded warehouse under the customs laws on the date any prohibition of their sale or removal, by any Act of Congress, or proclamation of the President of the United States takes effect shall be permitted to remain therein without payment of any taxes or duties thereon, beyond the three-year period provided by law, during such period of prohibition; and may be exported at any time during such extended period. Any imported spirits, wines, or other liquors as to which the three-year bonded period may have expired after February 24, 1919, and prior to the date such prohibition takes effect may at the option of the owner remain in bond during such period of prohibition.
19 U.S.C. § 460