46 U.S.C. § 60502: Discriminating duty on goods imported in foreign vessels or from contiguous countries

is entitled by law or treaty to enter the ports of the United States on payment of the same duties as are payable on goods imported in a vessel of the United States; or is owned only by citizens of the United States; and after entering a port of the United States, becomes documented as a vessel of the United States before leaving that port; or produced or manufactured in a foreign country not contiguous to the United States and imported from a country contiguous to the United States, unless imported in the usual course of strictly retail trade. If goods are imported without payment of the duty required by this section, the goods and the vessel in which they are imported may be seized by, and forfeited to, the United States Government.