The IMO and How a Convention Becomes Law

Read first: Legal Systems and Maritime Law: Civil Law, Common Law, Tort and the Maltese Courts. This topic explains who writes the international rules of shipping and when those rules start to bind your ship.

What the IMO Is

In short: the IMO is the United Nations specialised agency that writes the global rules for shipping.

• Main job: safety and security of shipping and prevention of pollution from ships (marine and atmospheric). It also encourages and helps States to apply these rules.
• The Convention on the IMO was adopted in Geneva on 6 March 1948 and entered into force on 17 March 1958. The body first met in 1959.
• Original name: IMCO (Inter-Governmental Maritime Consultative Organization). Renamed IMO in 1982. Headquarters: London.
• Membership: 176 Member States and 3 Associate Members (Hong Kong, China; Macao, China; the Faroes). Malta joined in 1966 (IMO, November 2026).
• On the bridge: almost every rule you work with — COLREG Structure, Application and Definitions, SOLAS, MARPOL, STCW — started as an IMO convention.

The Assembly

In short: the Assembly is the highest governing body. Every Member State sits in it.

• Made up of all Member States.
• Meets in regular session every 2 years (extraordinary sessions if needed).
• Approves the work programme and votes the budget.
• Elects the Council.
• Decisions in the Assembly (and in the Council) need a simple majority or a two-thirds majority, depending on the matter.

The Council

In short: the Council is the executive body. It supervises the work of the IMO between Assembly sessions.

• Elected by the Assembly for 2 years.
• 40 Member States for 2026–2027, in three categories (IMO):
  • Category A — 10 States with the largest interest in providing international shipping services (for example Italy, the UK, Greece, the USA).
  • Category B — 10 States with the largest interest in international seaborne trade (for example France).
  • Category C — 20 States with special interests in maritime transport or navigation, chosen so that all major regions of the world are represented. Malta sits in category C.
• The IMO has adopted amendments to enlarge the Council to 52 members. Until they enter into force, the Council stays at 40 — a good example of the gap between adoption and entry into force.

The Secretariat

In short: the Secretariat is the administrative body: the permanent staff who run the organisation day to day.

• About 300 international staff at the London headquarters.
• Led by the Secretary-General: Arsenio Dominguez (Panama), in office since 1 January 2024 for an initial 4-year term.
• The Secretary-General is the depositary of IMO conventions: States lodge their instruments of ratification with the IMO.

The Five Committees and Seven Sub-Committees

In short: the technical work is done in 5 committees, helped by 7 sub-committees.

The five committees

• Maritime Safety Committee (MSC) — the senior technical body: SOLAS, COLREG, STCW, navigation, LSA and fire safety.
• Marine Environment Protection Committee (MEPC) — MARPOL, ballast water, air emissions.
• Legal Committee (LEG) — liability, compensation and other legal questions.
• Technical Cooperation Committee (TC) — help to States that need support to apply IMO rules.
• Facilitation Committee (FAL) — cutting paperwork and delays for ships in port.

The seven sub-committees

They report to the MSC and/or the MEPC:

• HTW — Human Element, Training and Watchkeeping.
• III — Implementation of IMO Instruments.
• NCSR — Navigation, Communications and Search and Rescue.
• PPR — Pollution Prevention and Response.
• SDC — Ship Design and Construction.
• SSE — Ship Systems and Equipment.
• CCC — Carriage of Cargoes and Containers.

From Adoption to Entry into Force

In short: a convention goes through three steps — adoption by the IMO, ratification by each State, entry into force when enough States have ratified.

Adoption

• The formal acceptance by the IMO of the final text of the treaty, usually at a conference or in a committee.
• After adoption the text is ready for signature and ratification. It binds nobody yet.

Signature, ratification and accession

• Ratification: the act by which a State formally agrees to be legally bound by the treaty. The State deposits an instrument of ratification with the IMO.
• Signing “subject to ratification” does not bind a State; it lets the government finish its own legislative steps first.
• Acceptance and approval have the same effect as ratification.
• Accession: joining a treaty the State did not sign while it was open for signature.

Entry into force

• The moment the text becomes legally binding on the States that have ratified it.
• It happens when a minimum number of States (often also a minimum share of world merchant tonnage) have ratified, as written in the treaty’s own terms, usually after a set delay.
• Example: the Ballast Water Management Convention (adopted 2004) needed 30 States with 35 % of world merchant tonnage, then 12 months. The conditions were met on 8 September 2016; it entered into force on 8 September 2017 (IMO).
• Example: SOLAS 1974 was adopted on 1 November 1974 and entered into force on 25 May 1980.
• After that, each flag State makes the convention part of its national law (in Malta through the Merchant Shipping Act and its regulations).

Amendments and tacit acceptance

• Old method: an amendment needed explicit acceptance, usually by two-thirds of the Contracting States. This took years; some SOLAS 1960 amendments never came into force.
• Tacit acceptance (COLREG 1972, MARPOL, SOLAS 1974): an amendment enters into force on a set date unless enough Parties object before it.
• SOLAS Annex amendments: deemed accepted after 2 years (the MSC can shorten this, minimum 1 year) unless more than one-third of Contracting Governments, or Governments with at least 50 % of world gross tonnage, object (SOLAS Art. VIII).
• Result: most amendments enter into force within 18–24 months of adoption.

Conventions, Codes, Resolutions, Circulars and Recommendations

In short: only a convention binds by itself; the other instruments add detail, explain or advise.

• On the bridge: a new circular on ECDIS or a resolution on passage planning tells you how the IMO wants a rule applied. The legal duty itself comes from the convention and your flag State’s law.

Who Enforces IMO Rules

In short: the IMO has no police. Flag States and port States enforce its conventions.

• Flag State: makes the rules national law, surveys and certifies its ships, sets penalties, and is mainly responsible for offences on the high seas.
• Port State: may inspect foreign ships in its ports. Certificates are normally accepted, but a ship can be detained if there are clear grounds to believe its condition does not match its certificates (SOLAS 1974).
• Since the 1995 STCW amendments (in force 1 February 1997), the MSC reviews whether each Party meets the STCW training and certification rules (the STCW “White List”).
• Example: training, certification and Hours of Rest, Fatigue and Safe Manning come from STCW, but you are inspected against your flag State’s version of it. The same applies to the Bridge Equipment: SOLAS V/19 Carriage Requirements.