US Section 301 Tariff Probe Comment Period Active; Mexico Prepares Defense Before April 15 Deadline

The USTR's Section 301 trade investigation docket — opened March 17 after the February 2026 Supreme Court ruling struck down IEEPA tariffs — entered active comment period, with a Mexican government response due by April 15, 2026. The Section 301 process targets 'structural excess capacity' in manufacturing sectors including aluminum, automobiles, batteries, chemicals, electronics, semiconductors, and steel. Mexico's inclusion comes alongside 15+ other economies. A separate Section 301(b) forced-labor probe covers 60 economies. If USTR recommendations are adopted after the May 5 congressional hearing, new tariffs could be in place by late July 2026 — coinciding with the USMCA July 1 review deadline. Economy Secretary Ebrard's team was preparing submissions arguing Mexico's manufacturing sector meets USMCA rules of origin and does not constitute the 'excess capacity' described in the probe.