Insights · Compliance · Port State Control
When a flag state's oversight falls short, the port that a ship calls at becomes the backstop. Port State Control is the inspection regime that keeps substandard ships off the sea lanes — and the Paris MoU is the agreement that made it work across Europe.
Every seagoing ship is supposed to be policed by its flag state — the country it is registered in is responsible for surveying it, issuing its certificates and enforcing the international conventions it has signed up to. In practice some flag states do this rigorously and some barely at all. Port State Control exists to catch the ships that slip through. It is the inspection of a foreign ship by the authorities of the country whose port it has entered, and it has become one of the most effective levers in maritime safety.
A PSC officer does not invent the standard; they check the ship against the major international conventions that the flag state has ratified. The core instruments are:
A single port inspecting on its own is useful; a region inspecting in a coordinated way is far more powerful. The Paris Memorandum of Understanding on Port State Control, signed in 1982, brings together around 27 member maritime authorities across Europe and Canada to share inspection data and avoid both gaps and needless duplication. If a ship has just been thoroughly inspected in Rotterdam, the authorities in Antwerp or Le Havre can see that and direct their resources elsewhere.
The Paris MoU is not alone. The Tokyo MoU performs the same role across the Asia-Pacific, and the US Coast Guard runs its own port state programme. Together these regimes blanket most of the world's busy ports, which means a substandard ship struggles to find anywhere it can trade without scrutiny.
Inspectors cannot board every ship, so the Paris MoU uses a New Inspection Regime (NIR) to decide who gets looked at, how often and how deeply. Each vessel is assigned a risk profile — low, standard or high risk — calculated from a handful of factors:
A low-risk ship may go years between inspections; a high-risk ship can expect to be boarded on almost every visit. The regime quietly concentrates effort where the danger is.
If an inspection turns up deficiencies serious enough that the ship is unsafe to proceed, the officer issues a detention: the vessel is barred from sailing until the faults are corrected to the inspector's satisfaction. A detention is expensive — the ship sits idle, charters are missed, and the operator's fleet-wide risk score rises. Repeated detentions can escalate to a banning or refusal of access, locking a ship or even a whole flag out of the region's ports.
The flag state issues the certificate; the port state decides whether to believe it. A detention is the port state saying it does not. The logic of Port State Control under the Paris MoU
The Paris MoU publishes the results in the open. It maintains White, Grey and Black flag lists ranking registries by their detention performance, and it publishes lists of detained ships. Those records do not vanish: a vessel or flag with a string of detentions carries that history forward.
For anyone assessing a ship — a charterer, a financier, an insurer — the PSC record is one of the cleanest signals available. It is independent, it is conducted by state authorities, and it reflects the actual physical and operational condition of the vessel rather than a paper certificate. A pattern of detentions, deficiencies and a poor flag is exactly the profile that overlaps with the shadow fleet and with vessels worth screening hard. Marifest ties each vessel file to its IMO number so that flag standing and risk indicators sit alongside the sanctions screening across 97,000+ vessels, and you can read the same record whether you start from a ship search or a sanctions check.
How Marifest helps
Marifest surfaces the signals that Port State Control turns on — flag standing, ship type and age, operator track record — alongside sanctions standing on the same vessel file, so a risk picture builds up around the permanent IMO number.
Each ship's current flag is shown with its White, Grey or Black list standing, the first input the New Inspection Regime weighs.
Vessel type and build year sit on every record — the factors that push a ship toward a higher-risk inspection profile.
The operator and manager behind the hull are resolved, so a poor company track record can be tied to the whole fleet.
Everything is anchored to the IMO number, so a rename or reflagging never detaches a ship from its history.