A foreign-built, foreign-flagged factory ship may land processed seafood at a US port of entry, but the product is subject to FDA inspection (for fish and fishery products) or USDA FSIS inspection (for certain processed seafood products meeting the definition of 'fish of the order Siluriformes'). The vessel itself is not permitted to engage in US coastwise fishing under the Magnuson-Stevens Act and Jones Act without specific authorization.

A factory ship is equipped with onboard processing and preservation facilities—such as filleting lines, freezing tunnels, and canning equipment—that allow it to process catch at sea rather than returning raw fish to port. Standard fishing vessels lack these facilities and are classified based on their catching gear and hull design. The presence of integrated processing equipment is the key classification criterion separating factory ships from conventional fishing vessels.