Answer
the instruments issued by the International Maritime Organization (IMO) are broadly divided into two categories: Treaty Instruments (Mandatory Conventions like SOLAS, MARPOL, STCW, and Load Line) and Non-Treaty Instruments.
Non-treaty instruments are soft-law mechanisms, guidelines, and recommendations. While they are not standalone, legally binding treaties on their own, they carry immense regulatory weight. They often become mandatory through direct reference within a parent convention (e.g., the ISM Code within SOLAS Chapter IX) or are used by Port State Control (PSC) as the benchmark for safety.
The 4 Main Types of IMO Non-Treaty Instruments
The IMO utilizes four primary types of non-treaty instruments to regulate international shipping:
┌───────────────────────────────┐
│ IMO Non-Treaty Instruments │
└───────────────┬──────--------────────┘
┌────────────┼──────────┼──────────────┐
▼ ▼ ▼ ▼
[ Resolutions ] [ Codes ] [ Circulars ] RECOMMENDATION
1. IMO Assembly Resolutions (A. Resolutions)
The Assembly is the highest governing body of the IMO, consisting of all member states. Resolutions adopted during Assembly sessions outline global maritime policies, interpretations, and amendments.
Characteristics: They provide high-level technical guidance, strategic plans, and standard procedures for administrations.
Class 1 High-Focus Examples:
Res. A.1156(32): Survey Guidelines Under the Harmonized System of Survey and Certification (HSSC) – This dictates exactly how your class surveys are structured.
Res. A.1155(32): Procedures for Port State Control – The definitive manual used by PSCOs to inspect your vessel and issue Code 17 or Code 30 deficiencies.
Res. A.1047(27): Principles of Minimum Safe Manning – Governs the safe crew composition of your ship.
2. Codes (International Safety & Operational Standards)
Codes are comprehensive technical manuals developed by IMO sub-committees to address specific ship types, cargo hazards, or operational protocols.
The Conditional Binding Nature: A code on its own is a non-treaty instrument. However, once a SOLAS or MARPOL chapter states "Vessels shall comply with the provisions of Code X," that code instantly takes on the full legal, mandatory power of the parent treaty.
Class 1 High-Focus Examples:
The ISM Code (International Safety Management Code) – Made mandatory via SOLAS Chapter IX.
The ISPS Code (International Ship and Port Facility Security Code) – Made mandatory via SOLAS Chapter XI-2.
The CSS Code (Code of Safe Practice for Cargo Stowage and Securing) – Contains Annex 13, which governs your Cargo Securing Manual calculations.
The IMDG Code (International Maritime Dangerous Goods Code) – Mandated by SOLAS Chapter VII.
The NOx Technical Code – Governs marine diesel engine air pollution limits under MARPOL Annex VI.
3. Circulars (MSC, MEPC, and Sub-Committee Circulars)
Circulars are regular publications issued by key IMO committees, such as the Maritime Safety Committee (MSC) and the Marine Environment Protection Committee (MEPC).
Characteristics: They provide immediate technical clarifications, unified interpretations of complex rules, interim guidelines for emerging technologies (like alternative fuels), and notifications of safety deficiencies.
Class 1 High-Focus Examples:
MSC.1/Circ.1353/Rev.2: The official guidelines used for compiling the Cargo Securing Manual.
MEPC Circulars on Fuel Quality: Formally clarifying sampling points, bunker delivery notes, and low-sulfur fuel operational problems.
4. Recommendations and Guidelines
These are highly detailed technical publications that provide best practices for ship design, equipment installation, and crew operations.
Characteristics: They guide manufacturers, shipyards, and ship operators on how to reach the safety targets set by treaties.
Class 1 High-Focus Examples:
Guidelines on the Application of the IMO Performance Standard for Protective Coatings (PSPC).
Guidelines for the Development of Shipboard Oil Pollution Emergency Plans (SOPEP) under MARPOL Annex I.