19 U.S. Code § 2132 - Balance-of-payments authority
Import restricting actions proclaimed pursuant to subsection (a) of this section shall be of broad and uniform application with respect to product coverage except where the President determines, consistently with the purposes of this section, that certain articles should not be subject to import restricting actions because of the needs of the United States economy. Such exceptions shall be limited to the unavailability of domestic supply at reasonable prices, the necessary importation of raw materials, avoiding serious dislocations in the supply of imported goods, and other similar factors. In addition, uniform exceptions may be made where import restricting actions will be unnecessary or ineffective in carrying out the purposes of this section, such as with respect to articles already subject to import restrictions, goods in transit, or goods under binding contract. Neither the authorization of import restricting actions nor the determination of exceptions with respect to product coverage shall be made for the purpose of protecting individual domestic industries from import competition.
The President may at any time, consistent with the provisions of this section, suspend, modify, or terminate, in whole or in part, any proclamation under this section either during the initial 150-day period of effectiveness or as extended by subsequent Act of Congress.
No provision of law authorizing the termination of tariff concessions shall be used to impose a surcharge on imports into the United States.