Primary Authorities and Official Sources

The first five records form the smallest complete operative-authority set. The HTSUS supplies entry-level implementation. The remaining materials provide constitutional, judicial, treaty, regulatory, governmental, and economic context.

Core operative authorities

• 19 U.S.C. § 1338 — Discrimination by foreign countriesStatutory delegation invoked by the proclamations
• Proclamation 11046 · 91 Fed. Reg. 46639Canadian alcoholic beverages · HTSUS 9903.03.12
• Proclamation 11047 · 91 Fed. Reg. 46653Canadian dairy · HTSUS 9903.03.13
• Proclamation 11048 · 91 Fed. Reg. 46662Canadian motor vehicles and broader listed basket · HTSUS 9903.03.14
• Proclamation 11056 · 91 Fed. Reg. 54789Three-day suspension and effective-date amendment · signed August 18; effective August 22; Federal Register publication August 24

Implementation sources

• Harmonized Tariff Schedule of the United StatesDynamic source; preserve date-stamped Chapter 99 snapshots
• 19 U.S.C. § 2483Embodiment of tariff actions in the HTSUS
• 19 C.F.R. part 146, subpart DForeign-trade-zone merchandise status

Constitutional, judicial, and treaty context

• U.S. Constitution, Article I, Section 8Duties and foreign-commerce powers
• Learning Resources, Inc. v. TrumpIEEPA does not authorize presidential tariffs; Section 338 not decided
• USMCA Chapter 34Withdrawal, term, joint review, and extension

Official explanations and economic evidence

• USTR statement on the Section 338 tariffsAdministration explanation; not an operative instrument
• Chicago Fed tariff-line analysis569 categories; approximately $24 billion annualized; 5.5 percent of imports using May 2026 data
• Federal Reserve Board tariff-price researchConsumer-price pass-through evidence
• Bank of Canada Monetary Policy Report — January 2026Canadian outlook and trade-restriction effects
• Statistics Canada trade-developments reportCanadian export exposure and macroeconomic evidence
• U.S. Census Bureau — Trade in Goods with CanadaCurrent monthly bilateral goods data
• Government of Canada tariff-response portalCanadian sectoral measures, relief, and support
• Prime Minister Carney’s August 22 remarks on Canada–U.S. trade negotiationsOfficial announcement of Canada’s intended dollar-for-dollar response; explanatory source pending final implementing orders and tariff schedules

Public education and legal research only. Tariff liability depends on classification, origin, entry date, valuation, content rules, exclusions, foreign-trade-zone status, and later official guidance. Verify the current HTSUS and customs instructions before operational reliance.