Under the Jones Act, only US-built, US-flagged, and US-crewed vessels may transport cargo between US domestic ports. A foreign-built tanker imported into the US can legally operate in international trade or be sold to a foreign operator, but it cannot engage in US coastwise trade without a Jones Act waiver, which is rarely granted. This restriction is a primary reason most tanker imports are transactional rather than for domestic deployment.

CBP classifies a vessel as a tanker based on its primary design for liquid-bulk carriage, evidenced by features such as segregated cargo tanks, inert gas systems, and specialized pumping equipment. A combination carrier capable of carrying both dry bulk and liquid cargo may require a ruling to determine the correct heading, as the classification follows the vessel's principal design purpose rather than its current cargo.