Legal basis for IMERS, including the proposed differentiation, comprise:

  • UNCLOS convention defining the rights and responsibilities of nations in their use of the world's oceans
  • IOPC Funds precedent for direct funding
  • WTO rules that do not contradict a harmonized emission charge
  • GATT rules allow emission charges based on imports
  • MARPOL convention that could cover GHG emissions


The United Nations Convention on the Law of the Sea (UNCLOS) defines the rights and responsibilities of nations in their use of the world's oceans

. It codifies the principle of international customary law.

  • All waters beyond national boundaries are considered international waters — free to all nations, but belonging to none of them.

Dominance of International Law

UNCLOS aims to balance interests of international community and global commons, and therefore codifies the dominance of international law over national law in respect to the high seas.
The following articles are most relevant: 89 (invalidity of claims of sovereignty over the high seas) , 136 (common heritage of mankind), 137 (legal status of the area).
Regarding air pollution the following articles are most relevant: 212, 222.

Supra-national Approach and Equity

Although, UNCLOS does not explicitly regulate equitable division of revenues raised from international emission charges proposed it provides a very relevant analogy. The analogy are minerals discovered in the sea bed under the high seas, which are outside the sovereignty of any country. The revenue from exploitation of these minerals should be distributed equitably (article 140: Benefit of mankind).
In summary:
UNCLOS provides a firm legal framework for a supra-national approach proposed.

IOPC Funds

Within maritime industry there is already a legal precedent for a supra-national fund organization. The International Oil Pollution Compensation Funds (IOPC Funds) are three intergovernmental organisations which provide compensation for oil pollution damage resulting from spills of persistent oil from tankers. The organisations are: the 1971 Fund, 1992 Fund and the Supplementary Fund.
The importance of the precedent is that the contributions to the funds are direct, bypassing the national systems, thereby avoiding the so-called "domestic revenue problem".


World Trade Organization (WTO) and the UNFCCC have sustainable development as one of their objectives:

WTO, preamble

“Recognizing that their relations in the field of trade and economic endeavour should be conducted with a view to […] allowing for the optimal use of the world's resources in accordance with the objective of sustainable development, seeking both to protect and preserve the environment and to enhance the means for doing so in a manner consistent with [members’] respective needs and concerns at different levels of economic development”

Cross-references to International Trade in the Climate Change Regime

UNFCCC, art. 3(5):
“The Parties should cooperate to promote a supportive and open international economic system that would lead to sustainable economic growth and development in all Parties, particularly developing country Parties, thus enabling them better to address the problems of climate change. Measures taken to combat climate change, including unilateral ones, should not constitute a means of arbitrary or unjustifiable discrimination or a disguised restriction on international trade.”
A good source for materials and/or advice on the WTO aspect, if one still has doubts about the legality of harmonized charge as proposed, is the Centre for International Sustainable Development Law in Montreal, Canada.


General Agreement on Tariffs and Trade(GATT) prohibits differentiated treatments of goods based on their country of origin. As the proposed emission charges are not linked to the country of origin and to any specific goods directly, they conform with the GATT rules.
The conformity is achieved without the need to refer to the article XX that allows exemptions on the grounds of environmental protection.


The International Maritime Organization (IMO) develops and promulgates international regulation on air emissions from shipping.

    MARPOL 93/97 Annex VI was ratified in 2004, and entered into force on 19 May 2005.
  • Regulation 13 of Annex VI applies to emissions of nitrogen oxides (NOx)
  • Regulation 14 applies to sulphur oxides (SOx)
  • Regulation 15 applies to the emission of volatile organic compounds (VOCs)
  • Regulation 18 addresses fuel oil quality, particularly record keeping, fuel sampling and the issue of Bunker Delivery Notes (BDNs).
The sustained reduction in emissions from land based sources has focused attention on the relative contribution from shipping when near coastal areas and in ports. The IMO MEPC decided in July 2005 to evaluate whether a revision to Annex VI was required. This process is currently in progress and advice on revision will be considered by MEPC in March/April 2008.
A summary of the process and options being considered is available from IPIECA as document Maritime air emissions and MARPOL Annex VI (0.5 MB).

GHG addition to MARPOL Annex VI

The most straightforward approach to implement technical parts of legislation on the GHGs from shipping would therefore be to extend Annex VI for CO2, as the major GHG emitted by shipping. Time to enter into force of such amendment is likely to be 16 months. A route through a new convention would take many years.
Including CO2 or selected GHGs within Annex VI has the additional advantage of reuse of other regulations, notably the regulation 18 on BDNs.