May the individual carrier have the state enforce access to foreign ports unilaterally? Is unilateral retaliation under the purview of the US Federal Maritime Commission an exercise of extraterritoriality, and where does that leave port state authority? First, the article will establish the authority vested in the US Federal Maritime Commission to implement and enforce US ships’ access to ports abroad. Secondly, drawing on US unilateral retaliation against Japan over access to ports, resolved diplomatically in 1997, the article will discuss US unilateralism in shipping. Thirdly, the article will discuss the shape of extraterritoriality, and implications for port state authority. The article builds on and intervenes in literature on the role of Section 301 unilateralism and liberalization of maritime transport in US and in international trade law,([ ]) combined with literature on extraterritoriality in international private law, and on port states in maritime law.([ ]) The legal-empirical analysis fills a gap in scholarship between the fields of international trade law, international private law, and maritime law, and contributes to the existing conceptual framework and literature by introducing “constructive extraterritoriality”. This is particularly important at this time because the world is witnessing a trade war that sees US unilateralism front and center and simultaneously, global governance is seeing an increase in extraterritorial regulations.