If your ship calls at European or North Atlantic ports, several factors decide how often port state control officers come aboard. Only one of them is a straight choice you make as an owner: the flag. Its place on the Paris MoU white, grey and black list feeds into the ship's risk profile, and the risk profile sets the inspection interval. Understanding that chain is worth doing before you register a ship or change its flag, not after the first detention.
The Paris MoU in brief
The Paris Memorandum of Understanding on Port State Control is the joint inspection regime of the maritime administrations of Europe and the North Atlantic. Foreign-flagged ships calling at member ports are checked against the international conventions on safety, security, pollution prevention and seafarers' living and working conditions.
For a sense of scale: the Paris MoU 2025 Annual Report, published on 1 July 2026, records 16,474 inspections and 668 detentions in the region during 2025. A detention means the ship is not allowed to sail until serious deficiencies are put right, which for an owner translates directly into off-hire time, repair costs and awkward conversations with charterers.
How the white, grey and black list is built
Each year the Paris MoU places flag states on one of three lists according to their inspection and detention record:
- White List: flags with a consistently low detention record.
- Grey List: flags with an average record.
- Black List: flags with a poor record, graded further by level of risk.
The figures are not taken from a single year. The calculation uses inspection and detention data aggregated over the three previous calendar years, and a flag needs a minimum number of inspections in that window to be listed at all, so registries with little traffic in the region do not appear. A statistical formula turns the inspection and detention counts into an "excess factor", which decides both the list and the flag's rank within it.
New lists come out each year with the annual report. Because the three-year window rolls forward by a year each time, a flag's position tends to drift rather than jump, which is why the trend is often more telling than the current snapshot.
Class societies have a list too
Recognised organisations (ROs), the classification societies that issue statutory certificates on behalf of flags, are ranked in the same way. According to the 2025 Annual Report, an RO needs 60 or more inspections in the three-year period to be included. When a detainable deficiency is attributed to the RO, it is recorded as "RO responsible" and counts against that society's performance.
From list position to inspection interval
The Ship Risk Profile
Every ship in the Paris MoU region carries a Ship Risk Profile: low, standard or high risk. It is built from:
- Ship type and age
- The performance of the flag
- The performance of the recognised organisation (class)
- The performance of the ISM company
- The deficiencies and detentions found in the ship's own past inspections
A black-listed flag pushes a ship towards the high risk category. A white-listed flag, combined with good class, company and ship history, makes the low risk category reachable.
Inspection windows
The risk profile sets the window for the next periodic inspection. Under the inspection regime described on the Paris MoU website:
- High risk ships: every 5 to 6 months
- Standard risk ships: every 10 to 12 months
- Low risk ships: every 24 to 36 months
On top of these, additional inspections can be triggered by overriding or unexpected factors such as a complaint or an incident. Over a few years, the gap between a high risk and a low risk profile adds up to many more boardings, more hours of crew time spent on inspections and more chances of a deficiency being found.
The commercial side
The effect is not only operational. Charterers, terminals and vetting schemes look at a flag's port state control record. Repeated detentions can lead to a refusal of access to ports in the region, and the rules on refusal of access also take the flag's list position into account.
Reading the list when you choose a flag
- Look at the trend. A flag climbing from grey to white and one slipping from white to grey can sit side by side in a given year and tell opposite stories.
- Match the list to the trade. The Paris MoU covers Europe and the North Atlantic. The Tokyo MoU publishes its own white, grey and black list for the Asia-Pacific region, while the Mediterranean MoU, the Black Sea MoU and the US Coast Guard run their own assessments.
- Check the class society. A strong flag does not offset a weak RO record, because both count separately in the risk profile.
- Remember the ship's own history. A good flag will not, on its own, turn a ship with a record of deficiencies and detentions into a low risk ship.
- Weigh it against the other criteria. Not every white-listed flag suits every ship. Age rules, mortgage registration and annual charges vary from registry to registry.
Where to check the current position
Always check a flag's current position on the official Paris MoU site, parismou.org, against the latest annual report and performance lists. Because the lists change every year, brochures and older articles quoting a flag's position go out of date quickly. That is why we do not list individual flags' positions here. Whenever you compare flags, note which year's list you are looking at.
Help with choosing a flag
The Paris MoU list is one criterion among several, but it is not one to skip. Through our Flag Registration service we handle registration and change of flag under Panama, Palau, Liberia, Saint Kitts and Nevis, Comoros, Guinea-Bissau, Sierra Leone and Belize. Send us the ship's type, age and trading area, and we will compare those flags for you against the current Paris and Tokyo MoU lists.