Every imported carton carries a legal declaration, and the importer of record — not the freight forwarder, not the customs broker, not the foreign seller — is the party that signs it and answers for it. This UpLaw guide maps the whole of United States customs and trade-remedy law: the entry-liquidation-protest spine of the Tariff Act of 1930, the statutory duty of reasonable care created by the Customs Modernization Act, tariff classification under the Harmonized Tariff Schedule and its General Rules of Interpretation, customs valuation and the transaction-value hierarchy, rules of origin and the substantial-transformation test, and the duty-saving architecture of free trade agreements, drawback, and foreign trade zones. It then turns to the tariff machinery layered on top: antidumping and countervailing duties administered jointly by Commerce and the International Trade Commission, Section 201 safeguards, Section 232 national-security tariffs, and Section 301 action, together with the exclusion, scope, circumvention, and EAPA evasion proceedings that decide who actually pays. Finally it covers enforcement — Section 592 penalties and their fraud, gross negligence, and negligence tiers, the prior-disclosure lifeline, the focused assessment, forced-labor exclusion under Section 307 and the UFLPA rebuttable presumption, and intellectual property enforcement at the border and at the ITC under Section 337 — before ending at the Court of International Trade, where all of it is finally tested. A running hypothetical follows a kitchenware importer, Meridian Housewares, from a routine misclassification to a seven-figure penalty exposure. Tariff rates and program status change constantly; treat every number here as an illustration, not a quote.