46 U.S.C. § 60501 — Vessels allowed to import

(a) In General — Unless a treaty provides otherwise, goods may be imported into the United States from a foreign port or place only on (1) a vessel of the United States, or (2) a foreign vessel owned only by citizens or subjects of the country (A) where the goods are grown, produced, or manufactured, or (B) from which the goods can only be, or most usually are, first shipped for transportation. (b) Exception for Vessels of Countries Not Maintaining Similar Restrictions — Subsection (a) doesn't apply to a vessel of a foreign country that doesn't maintain a similar restriction against U.S.-documented vessels. (c) Exception for Vessels Becoming Documented — Subsection (a) doesn't apply to a vessel that (1) is owned only by U.S. citizens, and (2) becomes documented as a U.S. vessel before leaving the port it entered. (d) Seizure and Forfeiture — If goods are imported in violation of this section, the goods, and the vessel that carried them — along with its equipment and other cargo — may be seized by and forfeited to the U.S. government.