19 U.S.C. § 81c: Exemption from customs laws of merchandise brought into foreign trade zone

the draw-back, warehousing, and bonding, or any other provisions of the Tariff Act of 1930, as amended, and the regulations thereunder; and the statutes and bonds exacted for the payment of draw-back, refund, or exemption from liability for internal-revenue taxes and for the purposes of the internal-revenue laws generally and the regulations thereunder. The exemption from the customs laws of the United States provided under subsection (a) shall not be available on or before December 31, 1992 , to bicycle component parts unless such parts are reexported from the United States, whether in the original package, as components of a completely assembled bi­cycle, or otherwise. Notwithstanding the provisions of the fifth proviso of subsection (a), any article (within the meaning of section 5002(a)(14) of title 26 ) may be manufactured or produced from denatured distilled spirits which have been withdrawn free of tax from a distilled spirits plant (within the meaning of section 5002(a)(1) of title 26 ), and articles thereof, in a zone. Notwithstanding the provisions of the fifth proviso of subsection (a), distilled spirits which have been removed from a distilled spirits plant (as defined in section 5002(a)(1) of title 26 ) upon payment or determination of tax may be used in the manufacture or production of medicines, medicinal preparation, food products, flavors, or flavoring extracts, which are unfit for beverage purposes, in a zone. Such products will be eligible for drawback under the internal revenue laws under the same conditions applicable to similar manufacturing or production operations occurring in customs territory. In regard to the calculation of relative values in the operations of petroleum refineries in a foreign trade zone, the time of separation is defined as the entire manufacturing period. The price of products required for computing relative values shall be the average per unit value of each product for the manufacturing period. Definition and attribution of products to feedstocks for petroleum manufacturing may be either in accordance with Industry Standards of Potential Production on a Practical Operating Basis as verified and adopted by the Secretary of the Treasury (known as producibility) or such other inventory control method as approved by the Secretary of the Treasury that protects the revenue. Notwithstanding any other provision of law, if all applicable customs laws are complied with (except as otherwise provided in this subsection), merchandise which is admitted into a foreign trade zone for use within such zone as production equipment or as parts for such equipment, shall not be subject to duty until such merchandise is completely assembled, installed, tested, and used in the production for which it was admitted. The person who admits the merchandise described in paragraph (1) into the zone shall, at the time of such admission, certify to the Customs Service that the merchandise is admitted into the zone pursuant to this subsection for use within the zone as production equipment or as parts for such equipment and that the merchandise will be entered and estimated duties deposited when use of the merchandise in production begins. At the time use of the merchandise in production begins, the merchandise shall be entered, as provided for in section 484 of the Tariff Act of 1930 [ 19 U.S.C. 1484 ], and estimated duties shall be deposited with the Customs Service. The merchandise shall be subject to tariff classification according to its character, condition, and quantity, and at the rate of duty applicable, at the time use of the merchandise in production begins. For purposes of this subsection, the term “foreign trade zone” includes a subzone. take effect on the date on which the USMCA enters into force [ July 1, 2020 ]; and apply with respect to a good entered, or withdrawn from warehouse for consumption, on or after that date. the amendments made by subsections (b) through (e) shall not apply with respect to the good; and the provisions of law amended by such subsections, as such provisions were in effect on the day before that date, shall continue to apply on and after that date with respect to the good.”