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Port state control

Port state control (PSC) is the system by which a coastal or port state inspects foreign-flagged merchant ships calling at its ports to verify that the ship, its equipment, and its crew meet the minimum standards set by international maritime conventions. A port state has jurisdiction over every vessel in its waters regardless of the vessel’s flag, and PSC provides the principal enforcement backstop when flag states fail to maintain adequate oversight of ships registered under their authority. Inspections are conducted by qualified officers - known as PSC officers or surveyors - appointed by the relevant national authority, and ships found with serious deficiencies may be detained until those deficiencies are remedied. The regime is organised globally through nine regional Memoranda of Understanding (MoUs) and one bilateral agreement, collectively covering all major shipping lanes. ShipCalculators.com provides the PSC targeting factor calculator and the Paris MOU detention probability calculator to support compliance planning. A full listing of related tools is available in the ShipCalculators.com calculator catalogue.

Contents

Background and origins

The authority of a port state to inspect foreign ships derives ultimately from customary international law and, since 1982, from the United Nations Convention on the Law of the Sea (UNCLOS). Article 218 of UNCLOS gives port states the right to investigate alleged discharges in violation of applicable international rules that have occurred beyond their internal waters and even on the high seas, provided that the evidence is available in port. Article 219 requires port states to take administrative measures to prevent a ship from sailing if it poses an unreasonable threat of harm to the marine environment. These provisions gave a legal anchor to inspection practices that had already begun to emerge in regional agreements.

The underlying premise of PSC is the distinction between the flag state - the state whose nationality a ship holds under UNCLOS Article 91 and which bears primary responsibility for ensuring compliance - and the port state. Flag state control is exercised through surveys, certification, and the oversight of Recognised Organisations (classification societies) acting on the flag administration’s behalf. Where the flag state is unable or unwilling to perform this function adequately, the port state acts as a secondary layer of enforcement. This principle was articulated in SOLAS Regulation I/19 as early as 1974, in MARPOL Annex I Regulation 11 and Annex VI Regulation 10, in the Load Line Convention Article 21 (see load line), in the STCW Convention Article X, in MLC Title 5 (see MLC 2006), and in the ISM Code at SOLAS Regulation IX/6.3. The ISPS Code added a security dimension through SOLAS Regulation XI-2/9.

Amoco Cadiz and the Hague Memorandum

The immediate political catalyst for the first formal regional PSC agreement was the grounding of the very large crude carrier Amoco Cadiz on the rocks at Portsall, Brittany, on 16 March 1978. The vessel lost steering due to a hydraulic failure in her steering gear and, despite the intervention of a tug, grounded in heavy seas. The entire cargo of 223,000 tonnes of crude oil was released, producing the largest oil spill from a ship casualty up to that date and devastating the Breton coastline for months.

Investigations revealed that several European administrations had no coordinated mechanism for checking whether ships calling at their ports actually met the standards they were certified to hold. Certificates issued by flag states were accepted at face value. Deficiencies that an inspection would have identified - including the steering gear fault that contributed to the Amoco Cadiz loss - were invisible to port authorities.

Seven European nations - the Netherlands, Belgium, Denmark, Germany, France, the United Kingdom, and Sweden - met in The Hague and signed the Hague Memorandum of Understanding on Port State Control on 2 March 1978, before the wreck of the Amoco Cadiz had even finished breaking up. The Hague MoU committed the signatories to inspect at least 25% of foreign ships calling at their ports each year and to share inspection data. The instrument was provisional and narrow in scope, applying only to working conditions under the ILO Merchant Shipping (Minimum Standards) Convention No. 147, but it demonstrated the principle that regional information sharing could multiply the effectiveness of each national inspection programme.

Paris MOU 1982

The Hague MoU was superseded on 26 January 1982 when the Paris Memorandum of Understanding on Port State Control entered into force. The Paris MoU extended the scope of inspections to cover SOLAS, MARPOL, the Load Line Convention, and the STCW Convention in addition to ILO 147. The founding membership of 14 states grew progressively, and by the time of the 2023 annual report the Paris MoU had 27 member administrations including Canada (since 1994), Russia (since 1995), and Croatia. The Paris MoU secretariat is headquartered in Paris and maintains the THETIS database of all inspections carried out by member administrations.

The Paris MoU set the standard that at least 25% of foreign ships calling at member ports must be inspected each year, a figure subsequently tightened under the New Inspection Regime (NIR) introduced in 2011, which replaced the fixed 25% target with a risk-based selection model that guarantees more frequent inspections for higher-risk ships.

Proliferation of regional MoUs

The Paris MoU model was replicated across the world’s major shipping regions:

  • Acuerdo de Viña del Mar (Latin American Agreement): signed in Viña del Mar, Chile, in 1992; covers 13 Latin American states from Mexico southward through Argentina.
  • Tokyo MOU: signed in Tokyo in 1993 and entered into force in 1994; covers 21 Asia-Pacific administrations including China, Japan, Australia, and the Russian Federation (as a Pacific authority distinct from its Paris MoU membership). The Tokyo MoU conducts approximately 32,000 inspections per year, making it the largest single MoU by inspection volume.
  • Caribbean MOU: entered into force in 1996; covers Caribbean island states and territories.
  • Mediterranean MOU: entered into force in 1997; covers 10 Mediterranean states not already covered by the Paris MoU.
  • Indian Ocean MOU: entered into force in 1998; covers nine states bordering the Indian Ocean.
  • Abuja MOU: entered into force in 1999; covers West and Central African states.
  • Black Sea MOU: entered into force in 2000; covers six Black Sea riparian states.
  • Riyadh MOU (Gulf MOU): established 2004; covers the six Gulf Cooperation Council states.

All nine MoUs and the Viña del Mar Agreement are linked through the Memoranda of Understanding Concordat, an informal coordination mechanism that aligns inspection standards, shares detention information across databases, and prevents ships from fleeing a detention in one region to seek a more permissive port in another. A ship detained in Rotterdam under the Paris MoU will appear in the Tokyo MoU database as well.

United States Coast Guard regime

The United States operates its PSC programme independently of any MoU, under the authority of 46 CFR and the authority of the USCG. The US regime pre-dates the Paris MoU; American port state inspections of foreign-flag ships trace their statutory basis to the Ports and Waterways Safety Act 1972. The USCG publishes an annual Port State Control Report covering inspection statistics, flag performance, and deficiency trends. The PSIX database (Port State Information Exchange) records all inspections and is accessible to other MoU databases for cross-reference.

The QualShip 21 programme is the USCG’s voluntary quality-recognition scheme. Ships that have maintained a clean inspection record - no detentions and a deficiency rate below the average for their flag and ship type - over at least 36 consecutive months qualify for reduced inspection frequency. QualShip 21 status is reviewed annually and confers a commercial benefit as well as a safety signal: many charterers and terminal operators specifically ask whether a vessel holds QualShip 21 recognition.

Inspection regime and procedures

Conventions and instruments covered

PSC inspections can cover any mandatory IMO instrument or ILO convention that the port state has ratified. In practice the core inspection scope for Paris MoU and Tokyo MoU officers spans the following:

  • SOLAS: safety of construction, fire protection, life-saving appliances, radio, navigation equipment, ISM, ISPS, and the associated certificates (Safety Construction, Safety Equipment, Safety Radio, ISSC, Document of Compliance, Safety Management Certificate, Continuous Synopsis Record, Cargo Ship Safety Certificate).
  • MARPOL: Annex I (oil record book, oily water separator, IOPP Certificate), Annex II (noxious liquid substances), Annex IV (sewage), Annex V (garbage management plan and garbage record book), Annex VI (IAPP Certificate, sulphur compliance, SEEMP, CII rating document, EEXI Technical File).
  • International Load Line Convention (see load line): freeboard assignment, load line marks, structural conditions.
  • STCW Convention: certificates of competency, watchkeeping arrangements, rest-hour records.
  • MLC 2006: seafarer employment agreements, wage records, working-hours registers, accommodation, food, medical care, social security documentation, maritime labour certificate.
  • ISM Code: SMS documentation, non-conformity register, audit records, DOC and SMC validity.
  • ISPS Code: Ship Security Plan, ISSC, continuous synopsis record security entries, Ship Security Alert System test records.
  • Tonnage Convention 1969: International Tonnage Certificate (checked for consistency with Load Line and SOLAS certificates).
  • Ballast Water Management Convention (BWM Convention 2004): Ballast Water Management Certificate, Ballast Water Record Book.

The extent to which a PSC officer will examine each instrument in detail depends on the inspection type (initial, more detailed, or expanded), the deficiencies identified as the inspection progresses, and any targeted themes set by the current CIC.

Initial inspection

Every PSC inspection begins with an initial inspection. The PSC officer boards the ship and verifies that:

  • all certificates required under the applicable conventions are on board, apparently valid, and have not expired;
  • the ship’s overall condition - hull, equipment, crew - does not reveal obvious grounds for concern;
  • the crew complement corresponds to the Safe Manning Certificate and the officers hold certificates appropriate to their rank.

If the initial inspection reveals no deficiencies and the officer is satisfied, the inspection is recorded and the ship may proceed. The initial inspection is intentionally brief - typically one to two hours - to avoid placing a disproportionate administrative burden on ships that are already in good order.

More detailed inspection

If the initial inspection discloses one or more clear grounds for concern, the officer proceeds to a more detailed inspection. Clear grounds are defined by each MoU but typically include: certificates absent, expired, or apparently falsified; evidence of poor overall condition of the ship or equipment; a complaint by a crew member; information from a previous inspection; a report from a pilot, vessel traffic service, or harbour authority; or the ship being on a priority-selection list.

The more detailed inspection examines specific items in depth. The officer may check lifeboat release mechanisms, fire-detection panel records, oil record books (MARPOL Annex I), machinery logbooks, crew certificates and their endorsements, safety management system documentation, and working hours records (STCW and MLC). The scope of the more detailed inspection is guided by the deficiencies identified during the initial stage and by the applicable regulations.

More detailed inspection scope in practice

A more detailed inspection follows no single rigid template; the officer exercises judgment about which areas to probe based on what the initial check revealed. Common sequences include:

  • Fire safety: testing the fire alarm panel, opening a random selection of fire dampers to verify they close, checking CO2 cylinder seals and weight tags, inspecting portable extinguisher service labels, and walking through the engine room to verify that fixed fire-fighting systems are charged and operational. The ISM Code audit record may show whether crew fire drills have been carried out at the required frequency.
  • Life-saving appliances: launching controls tested (not necessarily a water launch, but operating the controls), immersion suit condition, EPIRB hydrostatic release date, liferaft service station certificate, SART battery date. Lifeboat engine start and secondary means of launching are verified.
  • MARPOL Annex I: the oil record book (ORB) is scrutinised for plausibility - entries for overboard discharges, machinery space bilge water processing, and sludge disposal are cross-checked against the ship’s operational pattern. A ship that has sailed 20 days without an ORB entry for bilge water processing is considered suspicious. The oily water separator (OWS) bypass valve is checked to ensure no unauthorised overboard route.
  • Manning and certification: certificates for the master, chief mate, chief engineer, and second engineer are verified for validity and for the appropriate STCW endorsement for the ship type and trading area. Rest-hour records for the past month are reviewed for compliance with STCW Regulation VIII/1 and MLC 2006 Standard A2.3.
  • ISM Code: the non-conformity register is reviewed to ensure that accidents and near-misses have been reported and corrective actions closed out, that the periodic internal audit has been completed, and that the last shore-based company audit or external verification is within the required period.

Expanded inspection

Certain categories of ships are required to receive an expanded inspection, which is more comprehensive than a more detailed inspection and covers a defined list of mandatory items. Under the Paris MoU NIR (2011), expanded inspections are mandatory for ships falling into 13 priority categories, including:

  • oil tankers over 15 years old;
  • chemical tankers over 10 years old (see chemical tanker);
  • bulk carriers over 12 years old (see bulk carrier);
  • gas carriers over 10 years old;
  • passenger ships on their periodical inspection;
  • other ship types over 12 years old that also carry a High Risk Ship (HRS) profile.

Expanded inspections cover areas including stability documentation, ISM compliance, fire safety equipment condition, life-saving appliance operability, structural condition (for bulk carriers and tankers), cargo securing (see cargo securing manual), and pollution prevention equipment. The Tokyo MoU adopted a similar expanded inspection framework in its own New Inspection Regime, which entered into force on 1 January 2014.

For an oil tanker subject to an expanded inspection, the officer will additionally check the condition of the inert gas system, segregated ballast capacity verification, the ODME (oil discharge monitoring equipment) and its calibration, and the crude oil washing (COW) documentation where applicable. For a bulk carrier, the expanded inspection includes an internal examination of at least one cargo hold and the hatch covers, a check of the bilge alarm system for each hold, and verification that the loading instrument is operational and that the stability booklet matches the current load condition.

Risk-based ship selection

Paris MOU New Inspection Regime

Before 2011, Paris MoU member states individually targeted ships for inspection subject to the 25% annual inspection rate target. The New Inspection Regime (NIR), introduced on 1 January 2011 and described in Paris MoU Annex 6, replaced this approach with a uniform, risk-based targeting formula applied across all member states. The NIR introduced the Ship Risk Profile (SRP), which classifies every ship due to call at a Paris MoU port into one of three categories:

  • High Risk Ship (HRS): attracts a mandatory inspection every six months or with priority weighting at every call.
  • Standard Risk Ship (SRS): inspected at intervals between six months and 12 months depending on weighted score.
  • Low Risk Ship (LRS): may be inspected less frequently, with intervals of up to 36 months.

The SRP score is computed from five weighted parameters: flag performance (white, grey, or black list status); ship type and age; Recognised Organisation (RO or classification society) performance; company performance (detention rate across the fleet); and individual ship inspection history (number of deficiencies and detentions in the previous 36 months). The PSC targeting factor calculator implements the Annex 6 formula, combining the flag score Sflag, the age/type score Stype, and adjustments for company and RO performance into the aggregate SRP score. A high aggregate score pushes the vessel toward HRS status and guarantees more frequent inspections.

The NIR also introduced the concept of priority targeting, by which certain ships are always selected regardless of risk profile: ships that have been detained in the previous six months, ships that have been refused access, and ships calling at a Paris MoU port for the first time.

Flag performance lists

The Paris MoU and Tokyo MoU each publish annual lists classifying flag states into three performance tiers based on the detention rate of their ships inspected in the preceding three years:

  • White list: flags with an above-average performance (low detention rate), indicating generally sound oversight by the flag administration.
  • Grey list: flags in a performance band around the average, under monitoring.
  • Black list: flags with a below-average performance, indicating systemic problems with flag state oversight.

A black-listed flag substantially increases the SRP score of every ship flying it, meaning ships under those flags face much more frequent PSC inspection. The list is recalculated annually based on a rolling three-year period and published in each MoU’s annual report. Flag administrations that consistently appear on the black list face reputational consequences: some charterers and oil majors blacklist ships registered under chronically listed flags, and some terminals refuse access entirely. The Paris MOU detention probability calculator incorporates flag list status into its risk output.

Deficiency categories and codes

Scope of deficiencies

When a PSC officer identifies a requirement that is not met, the non-compliance is recorded as a deficiency against the relevant convention and regulation. The Paris MoU uses a standardised system of deficiency codes (2020 edition) that categorises each deficiency by convention, chapter or annex, and sub-item. Major deficiency categories include:

  • SOLAS: fire safety systems (Chapter II-2), life-saving appliances (Chapter III), radio communications GMDSS (Chapter IV), navigation equipment (Chapter V), ISM Code (Chapter IX), ISPS Code (Chapter XI-2).
  • MARPOL: Annex I oil pollution prevention (oil record book, oily water separator, ORB entries), Annex VI air pollution prevention (sulphur content compliance, IAPP Certificate, shipboard SEEMP under IMO 2020 sulphur cap and EEXI/CII obligations).
  • MLC 2006: seafarer employment agreements, working and rest hours, wages, accommodation, food and catering, medical care, welfare.
  • Load Line Convention: assignment, marking, condition of freeboard deck (see load line).
  • ISM Code: non-conformities in the SMS, absence of Document of Compliance or Safety Management Certificate, failure to report accidents or near-misses.
  • STCW: certificates absent, expired or not appropriate to rank; rest-hour violations; inadequate familiarisation training.

According to the Paris MoU 2023 annual report, the most frequently cited deficiency categories were fire safety equipment, life-saving appliances, ISM Code compliance, MLC working and living conditions, and MARPOL Annex I record-keeping. Fire safety and life-saving appliances together consistently account for approximately 35-40% of all recorded deficiencies.

Action on deficiencies

Not every deficiency results in detention. PSC officers distinguish between deficiencies that require rectification before the ship sails and those that may be rectified at the next port of call or within a specified period without restricting the voyage. The criterion for detention is whether the deficiency, individually or in combination with others, constitutes a clear hazard to safety, health, or the environment such that it would be unreasonable to allow the ship to proceed.

A ship with a deficiency in its fire detection alarm but no other significant issues might be allowed to sail with an instruction to rectify at the next port. A ship with an inoperable main fire pump, a non-functional lifeboat release system, and a falsified oil record book would present a combination of deficiencies justifying detention. The judgement is left to the PSC officer, guided by published IMO guidelines (MSC-MEPC.4/Circ.2) and MoU procedures.

Detention

Detention criteria and procedure

A ship is formally detained when a PSC officer determines that the deficiencies found constitute a hazard to the ship, persons on board, or the marine environment serious enough to warrant withholding permission to sail. The detention is recorded in the MoU database and notified to the flag administration, the Recognised Organisation, and the ship’s owners or operators. The ship must remain in port until the deficiencies are remedied to the satisfaction of the PSC authority; in some cases an independent surveyor (appointed by the flag administration or RO) must verify the rectification.

The cost of a detention can be substantial: port dues, crew wages, fuel standby, cargo interests, and the charter rate all continue while the ship sits. Detention statistics form part of the performance data used to calculate flag list position. Under the Paris MoU NIR, a ship detained within the previous 36 months accumulates additional risk score, increasing the probability of being selected for inspection on future calls.

In 2023 the Paris MoU conducted approximately 18,000 inspections and recorded approximately 850 detentions, a detention rate of approximately 4.7%. The Tokyo MoU, with its larger inspection volume of approximately 32,000 inspections, reports similar detention rates. Detention rates vary significantly by flag: black-listed flags can reach detention rates of 10% or more, while white-listed flags typically record rates below two per cent.

Detention vs deficiency without detention

A deficiency recorded without detention (Action Code 30 in the Paris MoU system) requires the master to rectify the item and report the rectification to the PSC authority. Where the rectification requires specialist equipment or dry-dock attendance, the officer may accept an undertaking from the owner or flag administration. An Action Code 17 deficiency is one that requires detention, authorised by the PSC authority’s supervising officer. The distinction between 30 and 17 is the central exercise of professional judgement in PSC work and is the most contested aspect of PSC in any subsequent appeal.

Refusal of access and banning

The most severe sanction available under Paris MoU rules is a refusal of access to Paris MoU ports. A ship that has been detained three or more times within a 36-month period may be issued a refusal-of-access order under Paris MoU Regulation 15, prohibiting it from entering any Paris MoU port for a period of up to three months. A subsequent refusal extends the ban to 12 months; a further refusal extends it to 24 months; and the most persistent offenders face a 36-month exclusion from the entire Paris MoU area. Refusal of access is recorded in THETIS and communicated to all member administrations.

The refusal-of-access mechanism has significantly deterred substandard ship operators from continuing to trade to European and North Atlantic ports. However, it creates an incentive for flag shopping - reflagging to a jurisdiction outside the Paris MoU area. The Concordat between MoUs is designed to limit this escape route by sharing data, but MoU coverage in West Africa and parts of the Indian Ocean is thinner, and truly substandard ships can in principle migrate to routes where PSC scrutiny is less intense.

Concentrated Inspection Campaigns

Purpose and structure

Each year the Paris MoU and Tokyo MoU designate a Concentrated Inspection Campaign (CIC) - a focused three-month period during which PSC officers give priority attention to a specific area of compliance. The CIC mechanism allows the MoUs to direct enforcement effort toward known systemic weaknesses, generate statistical evidence of deficiency patterns, and send a clear compliance signal to the industry.

During a CIC, every ship that is inspected receives a targeted check on the CIC topic in addition to the normal inspection. The CIC questions are pre-published several months in advance, allowing operators to self-assess and correct deficiencies before the campaign begins. At the end of the campaign, the MoU publishes aggregated statistics showing compliance rates by ship type, flag, and deficiency sub-category.

Recent CIC topics

The selection of CIC topics reflects current enforcement priorities:

  • 2023: fire safety - specifically the operational readiness of fire-detection systems, fire-damper closure, portable fire extinguisher maintenance, and fire-pump capacity. The 2023 Paris MoU CIC found that fire safety deficiencies accounted for a disproportionate share of non-compliances even in ships that had otherwise clean records.
  • 2024: PSC guidance updates and MARPOL Annex VI compliance, reflecting the post-2023 implementation of EEXI and CII ratings and the associated survey obligations.
  • 2024-2025 joint CIC (Paris MoU and Tokyo MoU): STCW rest hours - specifically the completeness and integrity of records of hours of work and rest under STCW Regulation VIII/1 and MLC Standard A2.3. Rest-hour falsification has been a persistent concern since the 2010 Manila Amendments to STCW, and the joint campaign aims to quantify the extent of non-compliance and generate evidence for possible further regulatory action.

Electronic information systems

THETIS (Paris MOU)

THETIS is the inspection management database operated by the Paris MoU. Launched in 2011 to support the NIR, THETIS assigns each vessel an SRP score based on the five weighted parameters and a targeting priority (1 to 3) that PSC officers in member administrations consult when deciding which ships to inspect. THETIS records every inspection outcome, every deficiency, every detention, and every refusal of access across all 27 Paris MoU member administrations. Access is restricted to PSC authorities, flag administrations, and Recognised Organisations; ship operators can access summary information about their own fleet. The system is updated in real time as inspection reports are submitted.

THETIS-MED, a derivative system, serves the Mediterranean MoU. The Black Sea MoU and Indian Ocean MoU operate smaller national-system networks that feed data into the Concordat’s cross-MoU information exchange.

APCIS (Tokyo MOU)

APCIS (Asia-Pacific Computerised Information System) serves the Tokyo MoU. Like THETIS, APCIS records all inspections, deficiencies, and detentions across member administrations, calculates ship risk profiles, and supports the NIR targeting model adopted in 2014. APCIS integrates directly with the Tokyo MoU’s public “Port State Control of Tokyo MoU” portal, which publishes quarterly inspection reports and annual detention statistics for each flag state.

PSIX (USCG)

The USCG Port State Information Exchange (PSIX) database records all US port state inspections, including targeted examinations, safety examinations, and exams conducted as a result of specific deficiencies or complaints. PSIX data feed into the Concordat cross-MoU exchange; the USCG and Paris MoU share detention information bilaterally, meaning that a ship detained by the USCG will appear flagged in THETIS as well.

Interaction with flag state oversight

Flag state responsibility

PSC is an enforcement backstop, not a substitute for flag state control. Under SOLAS, MARPOL, STCW, and MLC, the primary obligation to ensure that ships meet the required standards rests with the flag administration - either directly through its own marine departments or indirectly through Recognised Organisations authorised to conduct surveys and issue certificates on the flag’s behalf.

The quality of flag state oversight varies considerably. Several open registries - Panama, Liberia, Marshall Islands, the Bahamas - delegate virtually all survey and certification functions to IACS member classification societies and maintain large maritime administrations that work closely with those societies. Others have thin administrative capacity and rely on ROs for almost everything, with minimal independent oversight. The IMO Member State Audit Scheme (IMSAS), which became mandatory under SOLAS Chapter XIII from 1 January 2016, subjects each IMO member state to a periodic audit of its legislative framework and administrative procedures; the flag state IMSAS audit calculator supports compliance planning for administrations preparing for an audit cycle.

Classification society performance

RO performance is one of the five parameters in the Paris MoU SRP formula. Classification societies whose certified ships show high PSC deficiency or detention rates accumulate a worse RO score, which is applied to every ship they certify. This creates a direct financial incentive for classification societies to maintain rigorous survey standards: a drop in RO performance increases PSC inspection frequency for all ships in the society’s fleet, imposing costs on clients and damaging the society’s commercial reputation.

Classification society oversight has been a recurring theme in major casualty investigations. Both the Erika (1999) and the Prestige (2002) losses involved tankers whose certificates had been maintained by societies subsequently criticised for inadequate survey practices. The Paris MoU published a Recognised Organisation performance list to make RO performance data publicly available, creating accountability not previously present in the system.

Company performance

The fifth SRP parameter - company performance - aggregates detention and deficiency data across all ships managed or operated by the same technical manager or owner within the Paris MoU inspection area. A company that manages a fleet with a chronic detention problem will see its SRP score applied to all ships it operates, even newly purchased vessels with a clean individual history. This parameter creates pressure on ship managers to maintain standards across the entire fleet rather than focusing resources on ships with the most imminent inspection due.

PSC officers: qualification and authority

PSC officers are appointed by the maritime authority of the port state and must meet minimum qualification standards set by the relevant MoU. The Paris MoU requires PSC officers to hold at minimum a Class I certificate of competency (master mariner or chief engineer) or an equivalent qualification from a recognised maritime college, and to complete a structured training programme covering all the conventions within the inspection scope. Newly qualified officers typically shadow experienced colleagues for a probationary period before conducting inspections independently.

The authority of a PSC officer within a port is domestic: they exercise the powers granted by the port state’s own legislation, not by the international convention directly. In most Paris MoU member states, the national maritime safety authority - such as the UK Maritime and Coastguard Agency, the Dutch Human Environment and Transport Inspectorate, or the French Direction des Affaires Maritimes - appoints PSC officers and grants them the legal power to board, inspect, and detain ships. The officer carries identification and documentation of their appointment; the master of the ship is obliged by the relevant domestic legislation to permit the inspection.

An officer who encounters obstruction - a master who refuses access, or crew instructed not to answer questions - can escalate to the harbour authority to prevent the ship from sailing, and in some jurisdictions the obstruction itself is a criminal offence. In practice such confrontations are rare; the commercial and reputational cost of detention or refusal of access greatly exceeds the inconvenience of cooperating with an inspection.

PSC officer training is increasingly formalised. EMSA (European Maritime Safety Agency) operates the EMSA PSC officers’ training programme for Paris MoU member states, covering inspection techniques, deficiency recording in THETIS, and the application of the NIR targeting model. IMO and the World Maritime University contribute to officer development through regional training seminars coordinated with the Indian Ocean, Abuja, and Black Sea MoUs, where inspection capacity is still being built up.

IMO frameworks supporting PSC

SOLAS Chapter XI-1 provisions

SOLAS Regulation XI-1/4, adopted in the 1995 SOLAS amendments package that explicitly formalised PSC, strengthened the right of PSC officers to verify the ISM Certificate, the International Ship Security Certificate, the Continuous Synopsis Record (CSR) required under Regulation XI-1/5, and the permanent IMO ship identification number required under Regulation XI-1/3. The CSR is a document that must be kept on board throughout the ship’s life, documenting all changes of name, flag, owner, registered company, and class, making it impossible for a ship to obscure its previous history through re-registration. The IMO number itself - assigned by IHS Markit (Lloyd’s Register Fairplay) on behalf of IMO - must be permanently marked on the hull or superstructure and in a machinery space frame, and cannot be changed when the ship changes flag or name.

CII and EEXI survey interface

The MARPOL Annex VI amendments adopted at MEPC 76 in June 2021, introducing the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator (CII), added a new dimension to PSC enforcement. Ships must carry an EEXI Technical File, a Statement of Compliance for the EEXI, and a CII rating document from 2023 onward. PSC officers have authority to check these documents and to verify that the ship’s Engine Power Limitation (EPL) device is installed and functioning. The what is EEXI and what is CII articles cover the underlying frameworks; the CII attained calculator and CII rating calculator support compliance assessment.

Ships operating under the EU Emissions Trading System must also carry documentation of their EU MRV monitoring plan and verified emissions report under EU ETS for shipping and IMO DCS vs EU MRV frameworks, items that PSC officers in EU member port states may check. Similarly, ships calling at European ports must demonstrate FuelEU Maritime compliance from 2025 onward.

The interaction between PSC and the CII framework is procedurally significant. A ship with a D or E rating under the CII rating scheme must carry a corrective action plan; PSC officers may verify that this plan exists and that it is being implemented, even though the CII scheme’s primary enforcement mechanism is flag state enforcement through the MARPOL survey cycle. Ships with exhaust gas cleaning systems (scrubbers) must carry documentation confirming that the scrubber is operating within its approved parameters; PSC officers in ports with scrubber wash-water restrictions may also check compliance with local port restrictions.

Ballast Water Management Convention

The BWM Convention, which entered into force in September 2017 and requires ships to treat ballast water before discharge, has become a standard item of PSC scrutiny. Ships must hold a valid International Ballast Water Management Certificate and a Ballast Water Management Plan, and must maintain a Ballast Water Record Book (BWRB) with entries for every ballast water exchange or treatment operation. PSC officers may physically inspect the ballast water treatment system to verify it is installed, operational, and of an approved type. Ships calling at US ports are subject to additional USCG ballast water requirements under 33 CFR Part 151, which in some cases are stricter than the D-2 performance standard of the BWM Convention.

Complaint handling and appeals

Crew complaints

One of the most valuable and underappreciated aspects of the PSC system is the right of crew members to complain directly to a PSC authority. Under MLC Title 5 and Paris MoU procedural guidelines, any seafarer may lodge a complaint with the PSC authority at a port, alleging non-compliance with MLC provisions on wages, working hours, accommodation, food, medical care, or repatriation rights. The PSC authority is required to investigate the complaint and, where it is found substantiated, to treat it as grounds for a more detailed inspection. The identity of the complainant is protected from disclosure to the shipowner or master during the inspection, though this protection has practical limits given the small crew sizes on many vessels.

Crew complaints have been an important channel for enforcing MLC 2006, which came into force in 2013 and introduced the first comprehensive port state control mechanism for labour standards in shipping. Prior to MLC, ILO Convention 147 provided a basis for inspection but with a much narrower scope and weaker enforcement mechanisms.

Appeals against detention

A ship operator who considers a detention to be unjustified may appeal to the relevant national authority. In Paris MoU member states, appeals are heard through the administrative or judicial procedures of the port state in question - there is no supranational Paris MoU appeals tribunal. The national authority may uphold the detention, modify it, or lift it. In practice, appeals against detention are relatively rare because by the time an appeal decision is reached the deficiency has usually been rectified and the ship has already sailed, making the dispute primarily a matter of compensation rather than operational freedom.

Where an operator believes that a PSC officer’s assessment was technically incorrect - for example, that a piece of equipment met the applicable standard despite the officer’s judgment to the contrary - the operator may request that the flag administration or the Recognised Organisation confirm the equipment’s compliance and present that assessment to the PSC authority. This process does not automatically lift the detention; the PSC officer retains authority pending the port state’s own review.

Modern practice and industry response

Pre-arrival preparation

Commercial operators have developed systematic pre-arrival PSC preparation procedures as part of the SMS required by the ISM Code. Pre-arrival checklists verify that all certificates are on board, valid, and not expiring within the voyage period; that logbooks and record books (oil record book, garbage management record, rest hour records) are complete and up to date; that life-saving appliances have been tested and results recorded; and that the ISM system’s non-conformity register is current. Many ship management companies employ dedicated PSC coordinators who monitor THETIS and APCIS for upcoming inspection due dates and track the company’s fleet-wide performance parameters.

The availability of THETIS data means that PSC officers know the ship’s complete inspection history before they board. A ship with two recent detentions and a pattern of fire safety deficiencies will receive a very different reception than a first-time visitor to the port with a clean record. Experienced PSC officers also cross-reference the ship’s current certificates against the expected renewal dates and may contact the Recognised Organisation before inspection if the certificate history raises questions.

Industry vetting programmes

PSC inspection results are also fed into commercial vetting systems. The SIRE (Ship Inspection Report Programme) operated by the Oil Companies International Marine Forum (OCIMF) covers tankers and gas carriers; the CDI (Chemical Distribution Institute) covers chemical tankers. Both systems collect independent inspection reports and make them available to cargo owners, charterers, and terminal operators. A recent PSC detention will typically appear in SIRE or CDI records and may result in a vessel being rejected by a charterer or refused entry to a terminal even after the PSC detention has been lifted.

The slow steaming and CII operational practices that have emerged in response to CII regulation have an indirect PSC dimension as well: a vessel operating at reduced speed accumulates a better CII rating, which improves its compliance documentation profile, reducing the probability of deficiency findings related to MARPOL Annex VI certificates during PSC.

Emerging areas: cyber security

IMO Resolution MSC-FAL.1/Circ.3, published in 2017 and requiring incorporation into the SMS by 1 January 2021, set the expectation that maritime cyber risks be addressed within the ISM Code framework. PSC officers may now ask to see documented evidence that the company has conducted a cyber risk assessment and incorporated cyber risk management into the SMS. The BIMCO Cyber Security Guidelines and the IACS UR E26 and E27 on cyber resilience for ships and onboard systems are the industry reference documents. This area is likely to become a more prominent feature of expanded inspections as PSC authorities develop officer training in digital systems verification.

Comparison of regional regimes

The nine MoUs and the Viña del Mar Agreement share the same legal basis and the same conventions they enforce, but differ in administrative capacity, inspection intensity, and enforcement follow-through.

The Paris MoU and Tokyo MoU are the most mature and technically advanced regimes. Both have adopted NIR risk-based targeting, both maintain large and well-integrated databases (THETIS and APCIS), both publish detailed annual reports, and both conduct joint CICs. Combined, the two MoUs account for approximately 50,000 inspections per year - the large majority of all global PSC inspections. Both also maintain formal cooperation agreements with the USCG, so that detention information flows across the Atlantic and the Pacific automatically.

The Indian Ocean MOU, Abuja MOU, and Black Sea MOU have developed their inspection capacity over time but operate with fewer resources. Detention rates in these regions can be higher not because the ships calling are necessarily worse but because the inspection process is less consistent and administrative capacity for follow-up is thinner. The Concordat’s data-sharing mechanisms help compensate for this by ensuring that detention records from these regions are visible to Paris and Tokyo MoU officers.

The Riyadh MOU covering the Gulf states is relatively young and has progressively strengthened its framework; the Gulf states are significant both as transit regions and as flag states for national shipping companies. The Caribbean MOU covers a large number of small island administrations with limited marine inspection resources.

The Viña del Mar Agreement is structured as a technical cooperation arrangement among the flag and port authorities of Latin American states, several of which are also both flag states and MoU members. It has strengthened PSC capacity across the region but does not have the same degree of database integration as the Paris and Tokyo MoUs.

Paris MOU 2023 data

The Paris MoU 2023 Annual Report recorded 17,942 individual ship inspections across 27 member administrations. Of these, 848 resulted in detention, a detention rate of 4.7%. Deficiencies were recorded in 10,643 inspections, meaning that approximately 59% of all inspected ships had at least one deficiency. The three highest-deficiency categories were fire safety equipment (2,847 deficiency items), life-saving appliances (2,119 items), and ISM Code compliance (1,983 items). MARPOL Annex I deficiencies numbered 1,412, and MLC deficiencies 1,378. Navigation equipment deficiencies totalled 987, with ECDIS update failure and voyage planning non-compliance prominent among sub-items.

Flags with the highest detention rates in the 2023 Paris MoU report were predominantly from the black list, with some recording rates above 10%. The best-performing flags - including Norway NIS, the Cayman Islands, and Denmark DIS - recorded detention rates below one per cent.

The Tokyo MoU 2023 Annual Report covered approximately 32,000 inspections. Detention rates show a long-term declining trend across both the Paris and Tokyo MoUs, from rates of around seven to nine per cent in the early 2000s to around four to five per cent today, reflecting both genuine improvement in fleet standards and the deterrent effect of risk-based targeting (which concentrates inspections on genuinely high-risk vessels rather than sampling randomly). The proportion of ships inspected that are free of deficiencies has risen steadily, reflecting industry investment in PSC preparation and SMS compliance.

See also

References

  1. Paris MoU on Port State Control. Annual Report 2023. Paris MoU Secretariat, Paris, 2024.
  2. Tokyo MoU on Port State Control. Annual Report 2023. Tokyo MoU Secretariat, Tokyo, 2024.
  3. IMO. International Convention for the Safety of Life at Sea (SOLAS), 1974, consolidated text. IMO, London, 2020 edition. Regulations I/19, XI-1/4, XI-1/5.
  4. IMO. MARPOL - Articles, Protocols, Annexes, Unified Interpretations, 6th edition. IMO, London, 2020. Annex I Regulation 11, Annex VI Regulation 10.
  5. IMO. International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW), 1978, 2011 consolidated edition. Article X.
  6. IMO. Maritime Labour Convention, 2006, 2013 consolidated edition. Title 5 (Standards A5.1-A5.4).
  7. IMO. International Convention on Load Lines, 1966 and Protocol of 1988, consolidated edition. Article 21.
  8. Paris MoU. New Inspection Regime - Annex 6: Targeting of Ships. Paris MoU, 2011, as amended 2020.
  9. Paris MoU. Concentrated Inspection Campaign 2023: Fire Safety - Final Report. Paris MoU Secretariat, 2024.
  10. IMO. Guidelines for Port State Control Officers on the ISM Code (MSC-MEPC.7/Circ.7). IMO, 2011.
  11. IMO. Guidelines on Port State Control under MARPOL Annex VI (MEPC.1/Circ.881). IMO, 2016.
  12. IMO. Member State Audit Scheme (IMSAS), mandatory from 1 January 2016, SOLAS Chapter XIII.
  13. IMO. Resolution MSC-FAL.1/Circ.3 - Guidelines on Maritime Cyber Risk Management. IMO, 2017.
  14. US Coast Guard. Port State Control 2022: Annual Report. USCG, Washington DC, 2023.
  15. Özçayir, Z.O. Port State Control, 2nd edition. LLP Professional Publishing, London, 2004.

Further reading

  • Molenaar, E.J. Coastal State Jurisdiction over Vessel-Source Pollution. Kluwer Law International, The Hague, 1998.
  • Kasoulides, G.C. Port State Control and Jurisdiction: Evolution of the Port State Regime. Martinus Nijhoff, Dordrecht, 1993.
  • Mitchell, R.B. Intentional Oil Pollution at Sea: Environmental Policy and Treaty Compliance. MIT Press, Cambridge MA, 1994.