HNS Convention enters force 29 November 2027 Readers follow

An international treaty governing liability for hazardous cargo spills at sea will enter into force on 29 November 2027, giving shipowners, cargo receivers and maritime administrations an eighteen-month window to prepare. The International Convention on Liability and Compensation for Damage in Connection with the Carriage of Hazardous and Noxious Substances by Sea — known as the HNS Convention — was first adopted in 1996, modelled on oil pollution civil liability conventions from the 1970s.

A diplomatic conference in April 2010 adopted a protocol to remedy defects in the original convention's reporting and contribution mechanisms, particularly regarding LNG cargo levies; the resulting instrument is the version now set to take effect. Under Article 21(1) of the 2010 Protocol, entry into force required ratification by at least twelve states, of which four must each operate a fleet of no less than two million gross tonnage units, alongside confirmation that contracting states collectively received at least forty million tonnes of contributing cargo in the preceding calendar year.

Both thresholds were satisfied on 29 May 2026, after Belgium, Germany, the Netherlands and Sweden ratified the previous month, bringing the total to twelve contracting states. The others are Canada, Denmark, Estonia, France, Norway, Slovakia, South Africa and Turkey. The Protocol mandates an eighteen-month gap between that triggering date and entry into force — hence 29 November 2027.

IMO Secretary-General Arsenio Dominguez described the milestone as closing "an important gap in the international liability and compensation regime for shipping," adding that the regime will give victims of hazardous cargo incidents access to fair, timely compensation while providing industry and governments legal certainty. The Convention establishes a two-tier compensation system. Tier 1 imposes strict shipowner liability regardless of fault, backed by compulsory state-certified insurance and an HNS certificate.

Shipowner liability is capped by gross tonnage, ranging broadly between ten million and one hundred million SDR for bulk HNS damage and rising to a maximum of 115 million SDR for packaged HNS or mixed bulk-and-packaged damage. Tier 2 is the HNS Fund, an intergovernmental mechanism financed by receivers of HNS cargo in contracting states; contributions are levied after an incident occurs and are calculated against compensation actually required, not collected in advance as a standing reserve.

Aggregate compensation across both tiers is capped at 250 million SDR per incident — roughly USD 360 million at current exchange rates. Where admissible claims fall within that cap they are paid in full; where they exceed it, payments are pro-rated proportionally among all claimants. Claims for death and personal injury are given priority in any payout.

Other recoverable heads of loss include property damage, pure economic loss, clean-up costs and environmental damage. The Convention covers more than 2,000 substances carried by sea, including chemicals, oils, acids, fertilisers, alcohols, LNG and LPG and addresses pollution damage, fire and explosion risk. An estimated 65,000 ships worldwide will be required to carry HNS certificates of insurance or equivalent financial security once the Convention takes effect.

Malta, which hosts one of the world's largest ship registries by gross tonnage, has not yet ratified the 2010 Protocol as of July 2026. Maltese-flagged vessels calling at ports of contracting states will nonetheless need to demonstrate HNS compliance from 29 November 2027, because the certification requirement attaches to port entry in contracting states regardless of the flag state's own ratification status.

Were Malta to ratify, it would assume Article 20 reporting obligations requiring Maltese authorities to track and report HNS cargo receipts through Maltese ports and terminals on an annual basis. This analysis was contributed by Gabriel DeBono, an Associate in the Shipping department at Ganado Advocates.