Dangerous substances at sea: an international framework finally operational from 2027 | Sea and Navy

The International Maritime Organization (IMO) has confirmed that the 2010 International Convention on Liability and Compensation for Damage in Connection with the Maritime Transport of Hazardous and Noxious Substances (HNS) will enter into force on 29 November 2027.

This entry into force comes after more than fifteen years of waiting. Adopted in its amended version in 2010, the text had until now failed to meet the conditions necessary for its application, due in particular to an insufficient number of ratifications and difficulties linked to the establishment of its financing mechanism. The required conditions were finally met at the end of May 2026, opening a transitional period of 18 months before its effective application. Twelve states have now ratified the convention. The system is based on two cumulative criteria: a minimum of 12 States Parties, several of which have significant tonnage, and the declaration of an annual volume of at least 40 million tonnes of contributing cargo. These conditions now being met, the regime becomes legally applicable.

The convention covers damage resulting from the maritime transport of more than 2,000 dangerous or noxious substances. This concerns in particular chemicals, liquefied gases (LNG and LPG), acids, fertilizers, alcohols as well as various substances transported in bulk or in packages. Compensable damages include human losses, injuries, property damage, economic losses, clean-up costs and environmental damage.

Owner liability and compensation fund

The regime is based on a two-tier accountability system. The first level corresponds to the strict liability of the ship owner, which must be covered by compulsory insurance or financial guarantee. The second level is ensured by an international compensation fund, which intervenes when the shipowner’s liability ceilings are exceeded. This fund is financed by receivers of HNS cargo in States Parties. The total amount of compensation is capped at around 250 million special drawing rights (or around $360 million) per event.

According to IMO estimates, around 65,000 ships will be required to hold a certificate of insurance or financial guarantee under the HNS Convention. The implementation of the system also requires the declaration of the cargoes concerned, a necessary condition for the operation of the compensation fund. The sectors mainly concerned include the transport of chemicals, liquefied gases as well as certain categories of fuels and industrial substances.

As of the end of May 2026, the 12 contracting states are: Belgium, Canada, Denmark, Estonia, France, Norway, the Netherlands, Slovakia, South Africa, Sweden and Turkey.