National-security authority behind steel, aluminum, and copper tariffs and their derivative-article coverage.
Section 232 of the Trade Expansion Act of 1962 lets the President impose duties on imports found to threaten national security, following a Commerce Department investigation. It is the authority behind the steel, aluminum, and copper tariffs, and reaches not only the raw metal but "derivative" articles made from it — meaning a manufactured product can carry a Section 232 duty because of the metal it's made of, not just its own classification. Coverage and relief mechanics (including melt-and-pour origin rules that can reduce the rate on qualifying North American-melted material) are specific to the product and the metal, which is why a duty determination has to check the actual HTS heading rather than assume the tariff applies uniformly across a chapter.
Trade Expansion Act of 1962, 19 U.S.C. 1862, implemented via Presidential Proclamations and HTSUS Chapter 99 headings (9903.8x.xx series).
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