2.3 Essential Aspects of IMO Law
2.3.1 The IMO – drafting the law of the sea
The IMO is an UN agency. Among its primary functions is the drafting of international legislation aimed at ensuring safety and security in global shipping.(1) Barbara Stępień, 'Navigating New Waters: IMO’s Efforts to Regulate Autonomous Shipping' (2024) 23 Chin. J. Int. Law. 599, 602. The broad international support of the IMO is evidenced by the near-universal ratification of its core conventions.(2) The International Maritime Organization, Status of Conventions (2025); Simon Baughen and Andrew Tettenborn, 'International Regulation of Shipping and Unmanned Vessels' in Bariş Soyer and Andrew Tettenborns (eds), Artificial Intelligence and Autonomous Shipping: Developing the International Legal Framework (Hart Publishing 2021) 7. The International Convention for the Safety of Life at Sea (SOLAS)(3) International Convention for the Safety of Life at Sea (adopted 1 November 1974, entered into force 25 May 1980) 1184 UNTS 278 (SOLAS). is undoubtedly the most important global convention for ship safety and equipment. It is ratified by 167 states, representing 99% of the commercial fleet of the world.(4) Andreas Osnes, SOLAS-konvensjonen (Store Norske Leksikon 2 October 2024). Similar to other IMO conventions, SOLAS requires its contracting parties to give the convention "full and complete effect" through domestic legislation.(5) SOLAS Article I b). The conventions of the IMO lack practical effect unless they are incorporated into national legislation and domestically enforced.(6)International Chamber of Shipping, Imo Conventions: Effective Implementation (International Chamber of Shipping 2014).
Because IMO law is incorporated into domestic law, the formal authority to interpret its provisions rests with the respective states. However, the IMO issues non-binding circulars that specify how the conventions should be interpreted and implemented in practice.(7) International Chamber of Shipping, Imo Conventions: Effective Implementation (International Chamber of Shipping 2014).
2.3.2 Existing regulations of ANS under IMO law
As stated in a 2023 report published by Lloyd's Register, the development of legal frameworks regulating AI in the shipping industry is likely to progress at a significantly slower pace than the development of the technology itself.(8) Sivori and Brunton (n 7) 28. Consistent with this, there is no comprehensive MASS-specific regulations in IMO law today.(9) Barbara Stępień, 'Navigating New Waters: IMO’s Efforts to Regulate Autonomous Shipping' (2024) 23 Chin. J. Int. Law. 599, 627-629. The IMO issued MASS-specific guidelines in 2019.(10) The International Maritime Organization, Interim Guidelines for Mass Trials, MSC.1/Circ.1604 (14 June 2019). However, these are brief, regard only trials with MASS, and were issued in a circular, which means that they, as a starting point, function as international soft law.(11) Referred to as "informal law" in Anna Petrig, 'Unconventional Law for Unconventional Ships? The Role of Informal Law in the International Maritime Organization’s Quest to Regulate Maritime Autonomous Surface Ships' Vessels' in Natalie Kleins (ed), Unconventional Lawmaking in the Law of the Sea (Oxford University Press 2022), Section 7.5.
Meanwhile, the existing conventions of the IMO apply to MASS. Some requirements currently pose clear obstacles to fully autonomous operations, for example in relation to watchkeeping standards.(12) International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (adopted 7 July 1978, entered into force 28 April 1984) 1361 UNTS 190 (STCW), Chapter VIII Regulation 2(2)(1) regarding constant physical presence of on-watch officers at the bridge of the ship. However, most of the current requirements do not, in themselves, prohibit MASS operations. The real issue is the significant uncertainty around what it means for autonomous ships to actually comply with the requirements, as the IMO had only conventional ships in mind when drafting the conventions.(13) Lloyd’s Register and Mitsui O.S.K. Lines (n 14) Section 4.4. This uncertainty is openly acknowledged by the IMO, and constituted a central element of the underlying rationale for the MASS Code initiative.(14) The draft MASS Code Preamble, para. 3.
2.3.3 The upcoming MASS Code and its regulation of ANS
The MASS Code, together with any relevant circulars, will specify how the existing conventions are to be understood when applied to MASS. The current draft of the Code establishes requirements for ANS specifically,(15) The draft MASS Code Chapter 17. complemented by general requirements regarding system design, software principles and alert functions that will also be of relevance to ANS.(16) The draft MASS Code Chapters 9, 10 and 14, respectively. Predictably, several of these requirements have no corresponding requirements in the current conventions.(17) Seungje Jin and Kwangil Lee, 'Gap analysis and harmonization of International Standards for Maritime Autonomous Surface Ships' (2024) 2867 J. Phys. 012051.
The MASS Code is scheduled for adoption at the IMO in a non-mandatory version in May 2026.(18) The draft MASS Code Annex II. Being non-mandatory, IMO member states do not need to implement it in domestic law right away, although they are welcome to. The IMO will then enter an "experience-building phase" with a view to revise the non-mandatory Code in 2028. The finalized and mandatory version of the Code is scheduled for adoption at the IMO in July 2030, entering into force in January 2032. It is not yet clear how the IMO will implement the mandatory Code within the conventional framework, but a new chapter in SOLAS is currently being considered.(19) The draft MASS Code Annex II This will, in practice, require the 167 states that have ratified SOLAS to give the Code effect within their national legislation.(20) SOLAS Articles I and VI.