A foreign-flagged vessel operating in U.S. waters must comply with U.S. federal law from the moment it enters the contiguous zone, and the rules stack up quickly: advance arrival notice to the Coast Guard, port state inspection on arrival, strict cabotage limits under the Jones Act, international safety and pollution standards enforced by U.S. inspectors, sanctions screening, and federal harbor taxes. The U.S. laws that apply to foreign-flagged vessels do not replace the ship’s flag state rules; they layer on top of them, and the Coast Guard has authority to detain any ship that falls short.
When U.S. Law Applies to a Foreign Ship
The United States can claim a territorial sea out to 12 nautical miles from its coastline and a contiguous zone reaching 24 nautical miles. Inside the territorial sea, the U.S. exercises full sovereignty. In the contiguous zone, it can enforce customs, immigration, fiscal, and sanitary regulations against foreign vessels.1United Nations. United Nations Convention on the Law of the Sea – Part II Territorial Sea and Contiguous Zone Innocent passage through territorial waters is generally allowed, but any activity threatening the peace, good order, or security of the coastal state can justify enforcement.
Once a foreign-flagged vessel enters a U.S. port, it is fully subject to U.S. domestic law. That covers customs, immigration, environmental rules, and security protocols under the Maritime Transportation Security Act and the International Ship and Port Facility Security Code, which SOLAS Chapter XI-2 made mandatory worldwide.2International Maritime Organization. International Convention for the Safety of Life at Sea
Advance Notice of Arrival
Before a foreign vessel physically shows up at a U.S. port, it must submit an electronic Notice of Arrival to the Coast Guard’s National Vessel Movement Center. For voyages of 96 hours or longer, the NOA must be filed at least 96 hours before arrival. For shorter voyages, filing must happen before departure and no later than 24 hours before arrival.3eCFR. 33 CFR 160.212 – When to Submit an NOA The filing includes vessel details, crew information, cargo, and last ports of call.
Port State Control Inspections
Port state control is the Coast Guard’s main tool for keeping foreign-flagged vessels in line. When a foreign ship calls at a U.S. port, Coast Guard inspectors can verify compliance with international conventions regardless of whether the flag state has done its job. The International Maritime Organization describes port state control as a safety net for catching substandard ships whose flag states have failed to regulate them.4International Maritime Organization. Port State Control The U.S. Coast Guard runs its own port state control regime, separate from the regional memoranda of understanding that cover Europe, Asia, and other regions.
Inspectors examine required certificates, the vessel’s structural condition, safety and pollution equipment, and crew qualifications. If deficiencies turn up, the port state can require immediate corrective action or detain the ship until problems are fixed. Detention is the strongest lever available. Every day a ship sits idle in port costs the operator money, so the threat alone drives compliance.
Cabotage: The Jones Act and the Passenger Rule
The single biggest restriction on foreign-flagged vessels in U.S. waters is cabotage. Under 46 U.S.C. § 55102, commonly called the Jones Act, cargo transported by water between two U.S. points must travel on a vessel that is U.S.-flagged, U.S.-built, and wholly owned by U.S. citizens with a coastwise endorsement.5Office of the Law Revision Counsel. 46 USC 55102 – Transportation of Merchandise A foreign-flagged ship cannot move freight from Houston to New York, no matter how competitive its rate.
The penalty is harsh. Cargo moved in violation is subject to seizure and forfeiture to the federal government. The government can instead recover either the value of the merchandise or the actual transportation cost, whichever is greater.5Office of the Law Revision Counsel. 46 USC 55102 – Transportation of Merchandise
A parallel rule under 46 U.S.C. § 55103 covers passengers. No vessel may carry passengers between U.S. ports unless it meets the same ownership, build, and documentation requirements. The penalty here is $300 per passenger transported and landed in violation.6Office of the Law Revision Counsel. 46 USC 55103 – Transportation of Passengers This is why cruise itineraries that begin and end in the United States almost always include a foreign stop in Mexico, Canada, or the Caribbean.
Jones Act Waivers
Waivers exist but are rare. Under 46 U.S.C. § 501, the head of the agency responsible for navigation laws may waive cabotage requirements when the Secretary of Defense determines it is necessary to address an immediate adverse effect on military operations. The Secretary must notify Congress within 24 hours and confirm that qualified U.S. vessels are unavailable. A separate provision allows a waiver when the President finds one necessary in the interest of national defense, but only after the Maritime Administrator certifies that no coastwise-qualified vessels can meet the need.7Office of the Law Revision Counsel. 46 USC 501 – Waiver of Navigation and Vessel-Inspection Laws These usually surface after hurricanes or during military mobilizations.
Safety, Pollution, and Crew Standards Enforced at U.S. Ports
Foreign-flagged vessels calling at U.S. ports must carry current certificates showing compliance with three major international conventions. Coast Guard inspectors verify each of them.
SOLAS
The International Convention for the Safety of Life at Sea spans 14 chapters covering ship construction, fire protection, life-saving appliances, radiocommunications, navigational safety, dangerous goods, and security. Flag states issue the certificates, but SOLAS itself authorizes port states to inspect and, if necessary, detain a foreign vessel that does not substantially comply.2International Maritime Organization. International Convention for the Safety of Life at Sea Required equipment includes voyage data recorders, automatic identification systems, and emergency position-indicating radio beacons. Vessels of 500 gross tonnage and above on international voyages must also comply with the International Safety Management Code and carry an International Ship Security Certificate under Chapter XI-2.
MARPOL
The International Convention for the Prevention of Pollution from Ships is organized into six annexes, each covering a different pollutant:8International Maritime Organization. International Convention for the Prevention of Pollution from Ships (MARPOL)
- Annex I: oil pollution from routine operations and accidents
- Annex II: noxious liquid substances in bulk
- Annex III: harmful substances in packaged form
- Annex IV: sewage from ships
- Annex V: garbage, including a complete ban on dumping plastics at sea
- Annex VI: air emissions, including sulfur oxide and nitrogen oxide limits
Vessels subject to Annex I must carry an International Oil Pollution Prevention Certificate confirming that required pollution prevention equipment is aboard and operational.9U.S. Coast Guard. MARPOL Annex I A missing certificate or malfunctioning equipment will support detention. Since 2020, Annex VI has imposed a global 0.50 percent sulfur cap on marine fuels, with tighter limits inside designated Emission Control Areas. Foreign vessels entering these zones must either burn compliant low-sulfur fuel or run approved exhaust gas cleaning systems.
The Maritime Labour Convention
The Maritime Labour Convention of 2006, often called the seafarers’ bill of rights, sets minimum standards for working and living conditions aboard commercial ships.10International Labour Organization. MLC, 2006 – What It Is and What It Does It covers 14 areas of shipboard life, including minimum age, medical certification, crew qualifications, employment agreements, hours of work and rest, wages, paid leave, medical care, accommodations, food, and health and safety.11International Labour Organization. Maritime Labour Convention, 2006
Every crew member must hold an approved Seafarer Employment Agreement. Ships of 500 gross tonnage and above engaged in international voyages must carry a Maritime Labour Certificate valid for up to five years, plus a Declaration of Maritime Labour Compliance. Part I of the declaration comes from the flag state; Part II is prepared by the shipowner and describes the specific measures keeping the vessel compliant between inspections.12International Labour Organization. Maritime Labour Convention, 2006 Frequently Asked Questions Port state inspectors verify these documents and can detain vessels with serious crew welfare deficiencies.
Sanctions Compliance
The U.S. Treasury Department’s Office of Foreign Assets Control has issued detailed sanctions guidance for the maritime industry. OFAC warns that sanctions liability can reach non-U.S. persons who cause U.S. persons to violate sanctions, evade them, or conspire to do so. Non-U.S. persons can also face secondary sanctions for facilitating significant transactions with blocked persons.13U.S. Department of the Treasury. Sanctions Guidance for the Maritime Shipping Industry
OFAC has flagged specific evasion patterns that draw scrutiny to a foreign-flagged vessel: manipulating Automatic Identification System data to disguise the ship’s location or identity, extended AIS silence in high-risk waters, sudden shipping-instruction changes, documentation modifications that mask sanctioned links, and refusals to provide information in response to standard due diligence requests.13U.S. Department of the Treasury. Sanctions Guidance for the Maritime Shipping Industry Owners, operators, charterers, and insurers all carry exposure when a vessel calls at a sanctioned port or carries cargo tied to a blocked entity.
Harbor Maintenance Tax and Port Fees
Foreign-flagged vessels calling at U.S. ports pay the federal Harbor Maintenance Tax, set at 0.125 percent of the value of commercial cargo loaded or unloaded. The tax is imposed at unloading and paid by the importer for incoming cargo or the shipper for outgoing cargo.14GovInfo. 26 USC 4461 – Imposition of Tax Flag makes no difference.
State-mandated pilotage fees add to the cost. Foreign-flagged vessels generally cannot navigate U.S. harbor channels without a state-licensed pilot aboard, and pilotage is treated as mandatory rather than optional. Port authorities also charge wharfage and dockage fees for berth space, and those vary widely by port and by vessel size.
FBAR Obligations for U.S. Owners
One reporting duty catches many people by surprise. A U.S. person who owns an interest in a foreign corporation that holds title to a foreign-flagged vessel may pick up separate financial reporting obligations tied to that corporation’s foreign bank accounts. If those foreign accounts exceed $10,000 in aggregate value at any point during the year, the U.S. owner must file FinCEN Form 114, the FBAR.15Financial Crimes Enforcement Network. Report Foreign Bank and Financial Accounts Missing the filing carries steep civil and, in willful cases, criminal penalties.
The rules above apply cumulatively. A foreign-flagged vessel entering the United States is answering to its flag state, to the Coast Guard, to Customs and Border Protection, to OFAC, to state pilotage authorities, and to the port itself, all at once. Compliance planning starts before the ship leaves its last foreign port, not on arrival.