Conventions, codes, resolutions and circulars: how do IMO instruments differ in legal force?

Why the type of instrument matters

The common phrase “IMO law” can refer to a treaty, protocol, amendment, code, resolution, circular or guideline; these instruments do not have the same legal rank. Before issuing an implementing order, a maritime manager must establish where the obligation comes from, when it became binding and whether the State or ship in question falls within its scope.

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Do not confuse the hierarchy with the title of the instrument

A convention creates obligations for Contracting Governments, subject to the rules on entry into force and scope of application. A code can become mandatory through a binding reference in a convention; Part A of the STCW Code is the well-known example of mandatory provisions, while Part B is guidance. A resolution is sometimes the vehicle for adopting a binding amendment and sometimes carries a recommendation. A circular is usually used for information or guidance, unless the relevant binding text gives it a different effect.

A four-step test of authority

First, find the exact number of the instrument and its amended version; second, identify the article or regulation that creates the obligation; third, separate the dates of adoption, tacit acceptance and entry into force; fourth, check the State’s accession and national implementation and any exemptions from scope. Relying on a quotation in a news item or a training slide without consulting the official text is not enough.

A decision example

Suppose a circular recommends the use of a new technology. A manager should not demand a firm statutory budget simply because the circular has been published. It must be established whether a binding regulation requires its use, whether national rules add any condition and what the compliance period is. Record the result of this review in a “legal status sheet” for the instrument.