The Legal Basis for IMO Climate Measures

By Aoife O’Leary, Jennifer Brown

This paper investigates the potential legal bases for the International Maritime Organization (IMO) to enact climate measures. It finds that the IMO has broad powers to enact almost any required measure, and quickly via a tacit amendment to the International Convention for the Prevention of Pollution from Ships (MARPOL).

The Convention on the International Maritime Organization establishes the IMO and gives it very broad objectives and powers to achieve those objectives. The objectives include the “prevention and control of marine pollution from ships.” The powers to achieve this objective include the drafting of conventions, agreements or other suitable instruments, and performing functions related to the objectives of the IMO. The powers are very broad and nowhere limit the type of marine pollution that the IMO Convention covers to exclude emissions of greenhouse gases. Indeed, state practice both within the IMO and in wider climate venues such as the United Nations Framework Convention on Climate Change (UNFCCC) confirm that members of the IMO interpret the term “marine pollution” to encompass greenhouse gases.

Once the power of the IMO to adopt economic measures or an independent body is established, the next question is what vehicle should be utilized. Climate measures should be legally binding, enforceable and implemented on a global scale as quickly as possible, as the climate crisis is urgent. The final section of this paper examines several options: the adoption of an entirely new treaty; the adoption of an entirely new agreement or other suitable instrument; or amending an already existing instrument. While all are possible, amending an existing instrument, most likely MARPOL, in the case of greenhouse gases, is the best option to ensure the fastest entry into force of the agreed measures, while also ensuring they are legally binding, enforceable and implemented globally.

There are two avenues for amending an existing annex to MARPOL, the “rejected unless accepted” procedure and the “accepted unless rejected” or tacit amendment procedure. The choice between the two procedures is purely a political decision and can be taken by the committee in which the proposed amendments are being discussed. The tacit amendment procedure can be utilized for the adoption of any amendments to an existing annex that do not go beyond the scope of the annex or MARPOL itself. The urgency of the climate crisis requires that the members of the IMO adopt effective climate measures by the tacit amendment procedure as soon as possible.

Read the report The Legal Basis for IMO Climate Measures in Columbia Law School's Scholarship Archive.