The Conference was held alongside the 44^th session of IMO's Marine Environment Protection Committee (MEPC), which met 6 to 13 March 2000.

Entry into force: Twelve months after ratification by not less than fifteen States, which are State Parties to the OPRC Convention.

Status: the fifteenth ratification was filed with IMO on 14 June 2006. The Protocol will therefore enter into force on 14 June 2007.

Introduction
The Protocol on Preparedness, Response and Co-operation to pollution Incidents by Hazardous and Noxious Substances, 2000 (HNS Protocol) follows the principles of the International Convention on Oil Pollution Preparedness, Response and Co-operation, 1990 (OPRC) and was formally adopted by States already Party to the OPRC Convention at a Diplomatic Conference held at IMO headquarters in London in March 2000.

Entry into force will be twelve months after ratification by not less than fifteen States, which are State parties to the OPRC Convention. The fifteenth state ratified the HNS Protocol on 14 June 2006. The Protocol will therefore enter into force on 14 June 2007.

Like the OPRC Convention, the HNS Protocol aims to provide a global framework for international co-operation in combating major incidents or threats of marine pollution. Parties to the HNS Protocol will be required to establish measures for dealing with pollution incidents, either nationally or in co-operation with other countries. Ships will be required to carry a shipboard pollution emergency plan to deal specifically with incidents involving HNS.

HNS definition
For the purposes of the HNS Protocol, a Hazardous and Noxious Substance is defined as any substance other than oil which, if introduced into the marine environment is likely to create hazards to human health, to harm living resources and marine life, to damage amenities or to interfere with other legitimate uses of the sea.

The HNS Protocol will ensure that ships carrying hazardous and noxious liquid substances are covered by preparedness and response regimes similar to those already in existence for oil incidents.

In 1996, IMO adopted the International Convention on Liability and Compensation for Damage in Connection with the Carriage of Hazardous and Noxious Substances (HNS) by sea, which provides for a compensation and liability regime for incidents involving these substances (it has not yet entered into force).
Liability and compensation regimes for oil pollution incidents are covered by the 1992 Protocols to the International Convention on Civil Liability for Oil Pollution Damage, 1969 and the International Convention on the Establishment of an International Fund for Compensation for Oil Pollution Damage, 1971.

Note: It should be noted that the definition of an HNS as defined by the OPRC-HNS Protocol 2000 differs widely from the definition of an HNS under the International Convention on Liability and Compensation for Damage in Connection with the Carriage of Hazardous and Noxious Substances (HNS) by sea, otherwise knows as the HNS Convention